Re: Mail server without MX record

[john]

Someone mentioned earlier that the OP (Jason Long) might be a bot.  
While I personally don't think this is the case, I do think we might be 
getting trolled...


A quick Google search shows that this same username\email is on several 
different sites recently asking similar questions for a variety of 
products.


Just my .02...

https://www.google.com/search?q=jason+long+hack3rcon

Re: Mail server without MX record.

[Jason Long]

Thank you.
I got my answer with your text.






On Friday, October 16, 2020, 02:19:20 PM GMT+3:30, Jaroslaw Rafa 
 wrote: 





Dnia 16.10.2020 o godz. 08:02:30 Jason Long pisze:

> Thank you.
> Thus, in Postfix or Dovecot configuration file I can't change the standard 
> record?


We already wrote you a few times, that DNS configuration (A/MX record) has
NOTHING TO DO with Postfix or Dovecot configuration. NOTHING. These are
COMPLETELY DIFFERENT SERVICES. Period.
-- 
Regards,
  Jaroslaw Rafa
  r...@rafa.eu.org
--
"In a million years, when kids go to school, they're gonna know: once there
was a Hushpuppy, and she lived with her daddy in the Bathtub."

Re: Mail server without MX record.

[Richard]

> Date: Friday, October 16, 2020 08:02:30 +
> From: Jason Long 

>> On Friday, October 16, 2020, 01:13:45 AM GMT+3:30, Richard
>> wrote: 
>> 
>> 
>>> Date: Thursday, October 15, 2020 18:57:29 +
>>> From: Jason Long 
>>> 
>>> If the DNS administrator give me an A record then can I sending 
>>> and receiving emails from the Internet by the current 
>>> configuration?  
>> 
>> Assuming no MX, if an A-record is set up to point to a  machine
>> (properly configured, including with postfix or some other MTA)
>> reachable on port 25 at the IPnumber, then it should be able to
>> receive mail inbound.
>> 
>> To be able to send mail directly to target mail servers you'll need
>> to be able to connect outbound on port 25. To successfully deliver
>> it, including to correspondents' inboxes, you'll need a matching
>> Rdns record as well as the following: 
>> 
>> (this list is taken from an earlier message from Ahsan Khan
>> responding to one of your questions):
>> 
>>   1. SPF
>>   2. DKIM records
>>   3. DMARC records
>>   4. IP Warmup
>>   5. Check the scores at mail-tester.com.
>>   6. Domain reputation
>> 
>>  There are a range of nitty things underlying all this which you 
>>  will need to read up on so that you understand how mail, DNS,
>>  etc. work.
>> 
>> You may be better off sending your mail outbound by way of a
>> smarthost at your provider.
>
> Thank you.
> Thus, in Postfix or Dovecot configuration file I can't change the
> standard record?
> 

Asked and already answered, multiple times, by various people.

It's also not clear how that question follows on from the q/a that it
is in reply to.

To run a mail server successfully takes a base-level knowledge of the
underlying protocols (and interoperability), not something gotten
from scattershot questions. Try looking at some of the references
previously mentioned.

Re: Mail server without MX record.

[Jaroslaw Rafa]

Dnia 16.10.2020 o godz. 08:02:30 Jason Long pisze:
> Thank you.
> Thus, in Postfix or Dovecot configuration file I can't change the standard 
> record?

We already wrote you a few times, that DNS configuration (A/MX record) has
NOTHING TO DO with Postfix or Dovecot configuration. NOTHING. These are
COMPLETELY DIFFERENT SERVICES. Period.
-- 
Regards,
   Jaroslaw Rafa
   r...@rafa.eu.org
--
"In a million years, when kids go to school, they're gonna know: once there
was a Hushpuppy, and she lived with her daddy in the Bathtub."

Re: Mail server without MX record.

[Bernardo Reino]

On Fri, 16 Oct 2020, Jason Long wrote:


Thank you.
Thus, in Postfix or Dovecot configuration file I can't change the standard 
record?


You a bot or something?

I think GPT-3 can understand more than you appear to do.

Good luck.

Re: Mail server without MX record.

[Jason Long]

Thank you.
Thus, in Postfix or Dovecot configuration file I can't change the standard 
record?






On Friday, October 16, 2020, 01:13:45 AM GMT+3:30, Richard 
 wrote: 







> Date: Thursday, October 15, 2020 18:57:29 +
> From: Jason Long 
>
> If the DNS administrator give me an A record then can I sending and
> receiving emails from the Internet by the current configuration?

> 

Assuming no MX, if an A-record is set up to point to a  machine
(properly configured, including with postfix or some other MTA)
reachable on port 25 at the IPnumber, then it should be able to
receive mail inbound.

To be able to send mail directly to target mail servers you'll need
to be able to connect outbound on port 25. To successfully deliver
it, including to correspondents' inboxes, you'll need a matching Rdns
record as well as the following: 

(this list is taken from an earlier message from Ahsan Khan
responding to one of your questions):

  1. SPF
  2. DKIM records
  3. DMARC records
  4. IP Warmup
  5. Check the scores at mail-tester.com.
  6. Domain reputation

There are a range of nitty things underlying all this which you will
need to read up on so that you understand how mail, DNS, etc. work.

You may be better off sending your mail outbound by way of a
smarthost at your provider.

Re: Mail server without MX record.

[Richard]

> Date: Thursday, October 15, 2020 18:57:29 +
> From: Jason Long 
>
> If the DNS administrator give me an A record then can I sending and
> receiving emails from the Internet by the current configuration?
> 

Assuming no MX, if an A-record is set up to point to a  machine
(properly configured, including with postfix or some other MTA)
reachable on port 25 at the IPnumber, then it should be able to
receive mail inbound.

To be able to send mail directly to target mail servers you'll need
to be able to connect outbound on port 25. To successfully deliver
it, including to correspondents' inboxes, you'll need a matching Rdns
record as well as the following: 

(this list is taken from an earlier message from Ahsan Khan
responding to one of your questions):

  1. SPF
  2. DKIM records
  3. DMARC records
  4. IP Warmup
  5. Check the scores at mail-tester.com.
  6. Domain reputation

There are a range of nitty things underlying all this which you will
need to read up on so that you understand how mail, DNS, etc. work.

You may be better off sending your mail outbound by way of a
smarthost at your provider.

Re: Mail server without MX record.

[Jason Long]

Thank you.
If the DNS administrator give me an A record then can I sending and receiving 
emails from the Internet by the current configuration?






On Thursday, October 15, 2020, 08:49:36 PM GMT+3:30, Wietse Venema 
 wrote: 





Jason Long:
> Thank you, but I never got my answer.1- Postfix or Dovecot has any
> option about changing default record that a mail server using?2-
> Could A record offer MX record in my goal?

An SMTP server cannnot tell remote systems what TCP port they should connect
to, or what DNS record they should ask for.

    Wietse


>  On Wed, Oct 14, 2020 at 10:09 PM, Wietse Venema wrote: 
> Jaroslaw Rafa:
> > Dnia 14.10.2020 o godz. 13:38:12 Wietse Venema pisze:
> > > Here's some email basics.
> > > 
> > > 1) You arrange for an MX and/or A record in your DNS zone. You edit
> > > the zone file yourself, or you use some provider's application to
> > > edit their zone file.
> > > 
> > >? ? example.com? ? ? ? 10 IN? MX? mail.example.com.
> > >? ? mail.example.com.? ? ? IN? ? A? 10.0.0.2
> > > 
> > > 2) SMTP uses destination port 25 for MTA-to-MTA traffic, therefore
> > > the port information is not in the DNS.
> > > 
> > > 3) Some remote MTA looks up your MX and/or A record and connects to
> > > your Postfix servers on port 25.
> > 
> > I think there's one important thing to add.
> > 
> > If you have a setup as above, then for mail addressed to "u...@example.com",
> > the remote MTA checks the MX record for example.com domain, finds out that
> > it points to mail.example.com, checks the A record for mail.example.com and
> > connects to the IP address found.
> > 
> > However, if the sender addresses the email to "u...@mail.example.com", the A
> > record for mail.example.com is sufficient to have mail delivered (assuming
> > your Postfix is configured to honor both example.com and mail.example.com
> > names as "mydestination"). The MX record for example.com domain is not
> > involved in the process, as the domain in the e-mail address is
> > mail.example.com and not example.com.
> > 
> > If there is another server within the example.com domain and it has it's own
> > independent Postfix instance, if you add A record for that server to the
> > zone file, you can send mail directly to it:
> > 
> >? ? othermail.example.com.? ? ? IN? ? A? 10.0.0.4
> > 
> > Then messages addressed to "u...@othermail.example.com" will go to that
> > other server, while messages to "u...@example.com" will still go to
> > mail.example.com.
> > 
> > You should not try to add another MX record for example.com domain pointing
> > to othermail.example.com, because if you do this, and email service on both
> > servers is not synchronized (which is not quite easy to do), the remote MTA
> > sending mail to "u...@example.com" will connect randomly to mail.example.com
> > or othermail.example.com, so the message will end up at random on one or the
> > other server (but never on both).
> 
> Except when the MX records have different preferences:
> 
> ? ? example.com? ? ? ? 10 IN? MX? mail.example.com.
> ? ? example.com? ? ? ? 20 IN? MX? othermail.example.com.
> ? ? mail.example.com.? ? ? IN? ? A? 10.0.0.2
> othermail.example.com.? ? ? IN? ? A? 10.0.0.4
> 
> Then, Postfix on othermail.example.com will forward u...@example.com
> to the primary MX host mail.example.com (assuming that mydestination
> is configured correctly, i.e. it does not contain example.com).
> 
> ??? Wietse
> 
>  

Re: Mail server without MX record.

[Wietse Venema]

Jason Long:
> Thank you, but I never got my answer.1- Postfix or Dovecot has any
> option about changing default record that a mail server using?2-
> Could A record offer MX record in my goal?

An SMTP server cannnot tell remote systems what TCP port they should connect
to, or what DNS record they should ask for.

Wietse

>   On Wed, Oct 14, 2020 at 10:09 PM, Wietse Venema 
> wrote:   Jaroslaw Rafa:
> > Dnia 14.10.2020 o godz. 13:38:12 Wietse Venema pisze:
> > > Here's some email basics.
> > > 
> > > 1) You arrange for an MX and/or A record in your DNS zone. You edit
> > > the zone file yourself, or you use some provider's application to
> > > edit their zone file.
> > > 
> > >? ? example.com? ? ? ? 10 IN? MX? mail.example.com.
> > >? ? mail.example.com.? ? ? IN? ? A? 10.0.0.2
> > > 
> > > 2) SMTP uses destination port 25 for MTA-to-MTA traffic, therefore
> > > the port information is not in the DNS.
> > > 
> > > 3) Some remote MTA looks up your MX and/or A record and connects to
> > > your Postfix servers on port 25.
> > 
> > I think there's one important thing to add.
> > 
> > If you have a setup as above, then for mail addressed to "u...@example.com",
> > the remote MTA checks the MX record for example.com domain, finds out that
> > it points to mail.example.com, checks the A record for mail.example.com and
> > connects to the IP address found.
> > 
> > However, if the sender addresses the email to "u...@mail.example.com", the A
> > record for mail.example.com is sufficient to have mail delivered (assuming
> > your Postfix is configured to honor both example.com and mail.example.com
> > names as "mydestination"). The MX record for example.com domain is not
> > involved in the process, as the domain in the e-mail address is
> > mail.example.com and not example.com.
> > 
> > If there is another server within the example.com domain and it has it's own
> > independent Postfix instance, if you add A record for that server to the
> > zone file, you can send mail directly to it:
> > 
> >? ? othermail.example.com.? ? ? IN? ? A? 10.0.0.4
> > 
> > Then messages addressed to "u...@othermail.example.com" will go to that
> > other server, while messages to "u...@example.com" will still go to
> > mail.example.com.
> > 
> > You should not try to add another MX record for example.com domain pointing
> > to othermail.example.com, because if you do this, and email service on both
> > servers is not synchronized (which is not quite easy to do), the remote MTA
> > sending mail to "u...@example.com" will connect randomly to mail.example.com
> > or othermail.example.com, so the message will end up at random on one or the
> > other server (but never on both).
> 
> Except when the MX records have different preferences:
> 
> ? ? example.com? ? ? ? 10 IN? MX? mail.example.com.
> ? ? example.com? ? ? ? 20 IN? MX? othermail.example.com.
> ? ? mail.example.com.? ? ? IN? ? A? 10.0.0.2
> othermail.example.com.? ? ? IN? ? A? 10.0.0.4
> 
> Then, Postfix on othermail.example.com will forward u...@example.com
> to the primary MX host mail.example.com (assuming that mydestination
> is configured correctly, i.e. it does not contain example.com).
> 
> ??? Wietse
> 
>   

Re: Mail server without MX record.

[Jason Long]

Thank you, but I never got my answer.1- Postfix or Dovecot has any option about 
changing default record that a mail server using?2- Could A record offer MX 
record in my goal?
 
 
  On Wed, Oct 14, 2020 at 10:09 PM, Wietse Venema wrote:  
 Jaroslaw Rafa:
> Dnia 14.10.2020 o godz. 13:38:12 Wietse Venema pisze:
> > Here's some email basics.
> > 
> > 1) You arrange for an MX and/or A record in your DNS zone. You edit
> > the zone file yourself, or you use some provider's application to
> > edit their zone file.
> > 
> >    example.com        10 IN  MX  mail.example.com.
> >    mail.example.com.      IN    A  10.0.0.2
> > 
> > 2) SMTP uses destination port 25 for MTA-to-MTA traffic, therefore
> > the port information is not in the DNS.
> > 
> > 3) Some remote MTA looks up your MX and/or A record and connects to
> > your Postfix servers on port 25.
> 
> I think there's one important thing to add.
> 
> If you have a setup as above, then for mail addressed to "u...@example.com",
> the remote MTA checks the MX record for example.com domain, finds out that
> it points to mail.example.com, checks the A record for mail.example.com and
> connects to the IP address found.
> 
> However, if the sender addresses the email to "u...@mail.example.com", the A
> record for mail.example.com is sufficient to have mail delivered (assuming
> your Postfix is configured to honor both example.com and mail.example.com
> names as "mydestination"). The MX record for example.com domain is not
> involved in the process, as the domain in the e-mail address is
> mail.example.com and not example.com.
> 
> If there is another server within the example.com domain and it has it's own
> independent Postfix instance, if you add A record for that server to the
> zone file, you can send mail directly to it:
> 
>    othermail.example.com.      IN    A  10.0.0.4
> 
> Then messages addressed to "u...@othermail.example.com" will go to that
> other server, while messages to "u...@example.com" will still go to
> mail.example.com.
> 
> You should not try to add another MX record for example.com domain pointing
> to othermail.example.com, because if you do this, and email service on both
> servers is not synchronized (which is not quite easy to do), the remote MTA
> sending mail to "u...@example.com" will connect randomly to mail.example.com
> or othermail.example.com, so the message will end up at random on one or the
> other server (but never on both).

Except when the MX records have different preferences:

    example.com        10 IN  MX  mail.example.com.
    example.com        20 IN  MX  othermail.example.com.
    mail.example.com.      IN    A  10.0.0.2
othermail.example.com.      IN    A  10.0.0.4

Then, Postfix on othermail.example.com will forward u...@example.com
to the primary MX host mail.example.com (assuming that mydestination
is configured correctly, i.e. it does not contain example.com).

    Wietse

  

Re: Mail server without MX record.

[Ron Wheeler]

There were a lot of answers given but the questions showed that the 
person asking the questions did not have the background in DNS and SMTP 
to take advantage of the answers and needed to take a bit of time with 
books or Google to develop enough understanding to know what to ask and 
how to interpret the answers.


We all have businesses to run or work of our own to do.

If you do not want to read and get the basic understanding required, you 
hire a consultant.


This is not a public school or a free consulting agency.

That is as polite a response as I can manage.

It is unseemly to complain about people who are trying to help you and 
are giving you the advice that you need to successfully accomplish the 
task that you have been given.


You will be much happier after you have read the introduction to the 
book and the chapters that apply to your problem.
You will also be in a much better position to deal with the next 
roadblock that you will hit; and you will have a lot more fun before you 
have a email server doing what you want.



Ron


On 2020-10-14 9:56 a.m., Jason Long wrote:

It is so odd that some people here don't like to answer to the users questions 
and forwarding them to read a book with 496 pages.






On Wednesday, October 14, 2020, 10:42:08 AM GMT+3:30, Viktor Dukhovni 
 wrote:





On Wed, Oct 14, 2020 at 07:04:25AM +, Jason Long wrote:



Can you tell me how can I setup my Postfix server with A record Or how
can I change the DNS server two support two MX records?


The gap between what your questions suggest you know, and what you need
to know to operate a mailserver is too wide to be adequately bridged on
this mailing list.  Asking questions here is no substitute for taking
the time to purchase and read some books on DNS, and Postfix.

For Postfix, the "No Starch Press" book by Ralf Hildebrandt and Patrick
Koetter is a good start, and may even get some of your DNS questions
answered.  You can start there, and if you still have DNS questions,
also read a DNS book.



--
Ron Wheeler
Artifact Software
438-345-3369
rwhee...@artifact-software.com

Re: Mail server without MX record.

[Wietse Venema]

Jaroslaw Rafa:
> Dnia 14.10.2020 o godz. 13:38:12 Wietse Venema pisze:
> > Here's some email basics.
> > 
> > 1) You arrange for an MX and/or A record in your DNS zone. You edit
> > the zone file yourself, or you use some provider's application to
> > edit their zone file.
> > 
> > example.com10 IN   MX  mail.example.com.
> > mail.example.com.  INA  10.0.0.2
> > 
> > 2) SMTP uses destination port 25 for MTA-to-MTA traffic, therefore
> > the port information is not in the DNS.
> > 
> > 3) Some remote MTA looks up your MX and/or A record and connects to
> > your Postfix servers on port 25.
> 
> I think there's one important thing to add.
> 
> If you have a setup as above, then for mail addressed to "u...@example.com",
> the remote MTA checks the MX record for example.com domain, finds out that
> it points to mail.example.com, checks the A record for mail.example.com and
> connects to the IP address found.
> 
> However, if the sender addresses the email to "u...@mail.example.com", the A
> record for mail.example.com is sufficient to have mail delivered (assuming
> your Postfix is configured to honor both example.com and mail.example.com
> names as "mydestination"). The MX record for example.com domain is not
> involved in the process, as the domain in the e-mail address is
> mail.example.com and not example.com.
> 
> If there is another server within the example.com domain and it has it's own
> independent Postfix instance, if you add A record for that server to the
> zone file, you can send mail directly to it:
> 
> othermail.example.com.  INA  10.0.0.4
> 
> Then messages addressed to "u...@othermail.example.com" will go to that
> other server, while messages to "u...@example.com" will still go to
> mail.example.com.
> 
> You should not try to add another MX record for example.com domain pointing
> to othermail.example.com, because if you do this, and email service on both
> servers is not synchronized (which is not quite easy to do), the remote MTA
> sending mail to "u...@example.com" will connect randomly to mail.example.com
> or othermail.example.com, so the message will end up at random on one or the
> other server (but never on both).

Except when the MX records have different preferences:

 example.com 10 IN   MX  mail.example.com.
 example.com 20 IN   MX  othermail.example.com.
 mail.example.com.  INA  10.0.0.2
othermail.example.com.  INA  10.0.0.4

Then, Postfix on othermail.example.com will forward u...@example.com
to the primary MX host mail.example.com (assuming that mydestination
is configured correctly, i.e. it does not contain example.com).

Wietse

Re: Mail server without MX record.

[Jaroslaw Rafa]

Dnia 14.10.2020 o godz. 13:38:12 Wietse Venema pisze:
> Here's some email basics.
> 
> 1) You arrange for an MX and/or A record in your DNS zone. You edit
> the zone file yourself, or you use some provider's application to
> edit their zone file.
> 
> exammple.com10 IN   MX  mail.example.com.
> mail.example.com.  INA  10.0.0.2
> 
> 2) SMTP uses destination port 25 for MTA-to-MTA traffic, therefore
> the port information is not in the DNS.
> 
> 3) Some remote MTA looks up your MX and/or A record and connects to
> your Postfix servers on port 25.

I think there's one important thing to add.

If you have a setup as above, then for mail addressed to "u...@example.com",
the remote MTA checks the MX record for example.com domain, finds out that
it points to mail.example.com, checks the A record for mail.example.com and
connects to the IP address found.

However, if the sender addresses the email to "u...@mail.example.com", the A
record for mail.example.com is sufficient to have mail delivered (assuming
your Postfix is configured to honor both example.com and mail.example.com
names as "mydestination"). The MX record for example.com domain is not
involved in the process, as the domain in the e-mail address is
mail.example.com and not example.com.

If there is another server within the example.com domain and it has it's own
independent Postfix instance, if you add A record for that server to the
zone file, you can send mail directly to it:

othermail.example.com.  INA  10.0.0.4

Then messages addressed to "u...@othermail.example.com" will go to that
other server, while messages to "u...@example.com" will still go to
mail.example.com.

You should not try to add another MX record for example.com domain pointing
to othermail.example.com, because if you do this, and email service on both
servers is not synchronized (which is not quite easy to do), the remote MTA
sending mail to "u...@example.com" will connect randomly to mail.example.com
or othermail.example.com, so the message will end up at random on one or the
other server (but never on both).

Hope this clarifies your doubts a bit...
-- 
Regards,
   Jaroslaw Rafa
   r...@rafa.eu.org
--
"In a million years, when kids go to school, they're gonna know: once there
was a Hushpuppy, and she lived with her daddy in the Bathtub."

Re: Mail server without MX record.

[Jaroslaw Rafa]

Dnia 14.10.2020 o godz. 17:03:05 Jason Long pisze:
> Thus with "https://wiki.centos.org/HowTos/postfix; tutorial I'm on a right
> track and Postfix doen't have any specific options about the selecting
> record? The Postfix server configured properly and the record option is
> not related to it?

Mail server (Postfix) and DNS (domain name server, where you define A and/or
MX records) are two completely different services, although they need to be
coordinated in order to get mail delivered to your mail server.

You found a tutorial on Postfix, take another step and find a tutorial on
configuring DNS service.
You can start for example with this one - it's the first one I found when
searching for "DNS configuration", although I don't guarantee it's the best
one:

https://www.wired.com/2010/02/set_up_a_dns_name_server/
-- 
Regards,
   Jaroslaw Rafa
   r...@rafa.eu.org
--
"In a million years, when kids go to school, they're gonna know: once there
was a Hushpuppy, and she lived with her daddy in the Bathtub."

Re: Mail server without MX record.

[Wietse Venema]

Jason Long:
> Thank you Kris.
> Thus with "https://wiki.centos.org/HowTos/postfix; tutorial I'm
> on a right track and Postfix doen't have any specific options about
> the selecting record? The Postfix server configured properly and
> the record option is not related to it?

Here's some email basics.

1) You arrange for an MX and/or A record in your DNS zone. You edit
the zone file yourself, or you use some provider's application to
edit their zone file.

exammple.com10 IN   MX  mail.example.com.
mail.example.com.  INA  10.0.0.2

2) SMTP uses destination port 25 for MTA-to-MTA traffic, therefore
the port information is not in the DNS.

3) Some remote MTA looks up your MX and/or A record and connects to
your Postfix servers on port 25.

Wietse
> 
> On Wednesday, October 14, 2020, 06:18:49 PM GMT+3:30, Kris Deugau 
>  wrote: 
> 
> Jason Long wrote:
> > Thank you.
> > Can you tell me how can I setup my Postfix server with A record
> 
> You just add an A record with a suitable name for your server.? There's 
> nothing Postfix-specific about this.
> 
> > Or how can I change the DNS server two support two MX records?
> 
> I'm not aware of any DNS server software that limits the number of MX 
> 
> records.
> 
> I *have* met all too many DNS management tools that make bad assumptions 
> about things like this.
> 
> You should talk to your IT support and/or hosting provider, because both 
> of these are specific to however your DNS records are managed, and 
> neither has anything to do with Postfix configuration.
> 
> -kgd
> 

Re: Mail server without MX record.

[Jason Long]

Thank you Kris.
Thus with "https://wiki.centos.org/HowTos/postfix; tutorial I'm on a right 
track and Postfix doen't have any specific options about the selecting record? 
The Postfix server configured properly and the record option is not related to 
it?







On Wednesday, October 14, 2020, 06:18:49 PM GMT+3:30, Kris Deugau 
 wrote: 





Jason Long wrote:
> Thank you.
> Can you tell me how can I setup my Postfix server with A record

You just add an A record with a suitable name for your server.  There's 
nothing Postfix-specific about this.

> Or how can I change the DNS server two support two MX records?

I'm not aware of any DNS server software that limits the number of MX 

records.


I *have* met all too many DNS management tools that make bad assumptions 
about things like this.

You should talk to your IT support and/or hosting provider, because both 
of these are specific to however your DNS records are managed, and 
neither has anything to do with Postfix configuration.

-kgd

Re: Mail server without MX record.

[Ron Wheeler]

Have you tried Google?
You can likely find whole tutorials answering both your questions.

Ron

On 2020-10-14 3:04 a.m., Jason Long wrote:

Thank you.
Can you tell me how can I setup my Postfix server with A record Or how can I 
change the DNS server two support two MX records?






On Tuesday, October 13, 2020, 11:09:22 PM GMT+3:30, IL Ka 
 wrote:






1- Each domain can have a MX record?

If you want to receive email for this domain then yes, you should have an MX record for 
it. Without it  "A" record will be used, but it is better to have MX.



2- If a company need multi MX record then it must have multi DNS server too?

You can have multiple MX records with different priorities. Sender's MTA will 
try first one first.
Number of DNS servers doesn't affect the number of MX records: in most cases 
all public servers must have the same records.



3- Other methods like forwarding need MX record too?

No, if you only want to send email, you are not required to have an MX record. 
Some MTAs may decline messages from domains without of MX, but most of them 
accept such mails.
But if you have no MX, then you can't get replies and non delivery reports.

There are some books about Postfix: "The book of Postfix", "Postfix: The Definitive 
Guide". It may be a good idea to read some of them: they cover how postfix works with DNS and 
MX.



On Tue, Oct 13, 2020 at 10:15 PM Jason Long  wrote:

I'm really thankful for all information and help.
Excuse me, I have some questions and I'm thankful if anyone answer to them by 
number:
1- Each domain can have a MX record?
2- If a company need multi MX record then it must have multi DNS server too?
3- Other methods like forwarding need MX record too?

Thank you.


Sent from Yahoo Mail on Android


   
   
On Tue, Oct 13, 2020 at 10:12 PM, @lbutlr

 wrote:


   On 13 Oct 2020, at 12:03, Fred Morris  wrote:


Notwithstanding, any "fully qualified domain name" (FQDN) can have email sent 
to it; typically only the FQDN immediately below the zone cut, and also the subject of 
SOA and NS records, has MX records.


Pretty sure it is prefect fine to have different MX records for subdomains.

example.com    MX    10    mail.example.com.
foo        MX    10    mail.sub1.example.com.
Bar        MX    10    mail.sub2.example.com.

Universities used to often have different MX servers for different 
departments/machines, though now it seems they are using external services for 
MX (maybe lucky, I checked five and all were using google or outlook for MX).

--
"Are you pondering what I'm pondering?"
"I think so, Brain, but Tuesday Weld isn't a complete sentence."





--
Ron Wheeler
Artifact Software
438-345-3369
rwhee...@artifact-software.com

Re: Mail server without MX record.

[Kris Deugau]

Jason Long wrote:

Thank you.
Can you tell me how can I setup my Postfix server with A record


You just add an A record with a suitable name for your server.  There's 
nothing Postfix-specific about this.



Or how can I change the DNS server two support two MX records?


I'm not aware of any DNS server software that limits the number of MX 
records.


I *have* met all too many DNS management tools that make bad assumptions 
about things like this.


You should talk to your IT support and/or hosting provider, because both 
of these are specific to however your DNS records are managed, and 
neither has anything to do with Postfix configuration.


-kgd

Re: Mail server without MX record.

[vi...@vheuser.com]

But it helps to know what bait is before you buy a fishing boat.
~v


On 2020/10/14 10:00 AM, Wietse Venema wrote:

Jason Long:

It is so odd that some people here don't like to answer to the
users questions and forwarding them to read a book with 496 pages.

Indeed, postfix-users is not a cargo-cult recipe factory.

Teach a man to fish, and they can feed themselves.

Wietse

Re: Mail server without MX record.

[Wietse Venema]

Jason Long:
> It is so odd that some people here don't like to answer to the
> users questions and forwarding them to read a book with 496 pages.

Indeed, postfix-users is not a cargo-cult recipe factory.

Teach a man to fish, and they can feed themselves.

Wietse

Re: Mail server without MX record.

[Jason Long]

It is so odd that some people here don't like to answer to the users questions 
and forwarding them to read a book with 496 pages.






On Wednesday, October 14, 2020, 10:42:08 AM GMT+3:30, Viktor Dukhovni 
 wrote: 





On Wed, Oct 14, 2020 at 07:04:25AM +, Jason Long wrote:


> Can you tell me how can I setup my Postfix server with A record Or how
> can I change the DNS server two support two MX records?


The gap between what your questions suggest you know, and what you need
to know to operate a mailserver is too wide to be adequately bridged on
this mailing list.  Asking questions here is no substitute for taking
the time to purchase and read some books on DNS, and Postfix.

For Postfix, the "No Starch Press" book by Ralf Hildebrandt and Patrick
Koetter is a good start, and may even get some of your DNS questions
answered.  You can start there, and if you still have DNS questions,
also read a DNS book.

-- 
    Viktor.

Re: Mail server without MX record.

[Viktor Dukhovni]

On Wed, Oct 14, 2020 at 07:04:25AM +, Jason Long wrote:

> Can you tell me how can I setup my Postfix server with A record Or how
> can I change the DNS server two support two MX records?

The gap between what your questions suggest you know, and what you need
to know to operate a mailserver is too wide to be adequately bridged on
this mailing list.  Asking questions here is no substitute for taking
the time to purchase and read some books on DNS, and Postfix.

For Postfix, the "No Starch Press" book by Ralf Hildebrandt and Patrick
Koetter is a good start, and may even get some of your DNS questions
answered.  You can start there, and if you still have DNS questions,
also read a DNS book.

-- 
Viktor.

Re: Mail server without MX record.

[Jason Long]

Thank you.
Can you tell me how can I setup my Postfix server with A record Or how can I 
change the DNS server two support two MX records?






On Tuesday, October 13, 2020, 11:09:22 PM GMT+3:30, IL Ka 
 wrote: 





>1- Each domain can have a MX record?
If you want to receive email for this domain then yes, you should have an MX 
record for it. Without it  "A" record will be used, but it is better to have MX.


>2- If a company need multi MX record then it must have multi DNS server too?
You can have multiple MX records with different priorities. Sender's MTA will 
try first one first.
Number of DNS servers doesn't affect the number of MX records: in most cases 
all public servers must have the same records.


>3- Other methods like forwarding need MX record too?
No, if you only want to send email, you are not required to have an MX record. 
Some MTAs may decline messages from domains without of MX, but most of them 
accept such mails.
But if you have no MX, then you can't get replies and non delivery reports. 

There are some books about Postfix: "The book of Postfix", "Postfix: The 
Definitive Guide". It may be a good idea to read some of them: they cover how 
postfix works with DNS and MX.



On Tue, Oct 13, 2020 at 10:15 PM Jason Long  wrote:
> I'm really thankful for all information and help.
> Excuse me, I have some questions and I'm thankful if anyone answer to them by 
> number:
> 1- Each domain can have a MX record?
> 2- If a company need multi MX record then it must have multi DNS server too?
> 3- Other methods like forwarding need MX record too?
> 
> Thank you.
> 
> 
> Sent from Yahoo Mail on Android
> 
> 
>>  
>>  
>> On Tue, Oct 13, 2020 at 10:12 PM, @lbutlr
>>  wrote:
>> 
>> 
>>  On 13 Oct 2020, at 12:03, Fred Morris  wrote:
>> 
>>> Notwithstanding, any "fully qualified domain name" (FQDN) can have email 
>>> sent to it; typically only the FQDN immediately below the zone cut, and 
>>> also the subject of SOA and NS records, has MX records.
>> 
>> 
>> Pretty sure it is prefect fine to have different MX records for subdomains.
>> 
>> example.com    MX    10    mail.example.com.
>> foo        MX    10    mail.sub1.example.com.
>> Bar        MX    10    mail.sub2.example.com.
>> 
>> Universities used to often have different MX servers for different 
>> departments/machines, though now it seems they are using external services 
>> for MX (maybe lucky, I checked five and all were using google or outlook for 
>> MX).
>> 
>> -- 
>> "Are you pondering what I'm pondering?"
>> "I think so, Brain, but Tuesday Weld isn't a complete sentence."
>> 
>> 
>> 

Re: Mail server without MX record.

[Dirk Stöcker]

On Tue, 13 Oct 2020, Fred Morris wrote:

Perfect, thanks! billmail.scconsult.com is not delegated from scconsult.com 
(has no SOA or NS), and sccconsult.com is delegated from .com (of course), 
with SOA and NS.


Bonus points: billmail has SPF.


Same concept, but a bit different (also has SPF, DANE, ...):

d.stoecker.eu -> 10 mail.stoecker.eu.

Subdomains for members of the family :-) Using only one MX for these
and the main domains.

Usually works fine except:
* Some clever web-interfaces assume that e-mail addresses can only have one dot
* Some more clever web-interfaces assume that a single letter before the dot 
isn't ok.

So it's not always possible to use the addresses.

Ciao
--
http://www.dstoecker.eu/ (PGP key available)

Re: Mail server without MX record.

[Fred Morris]

On Tue, 13 Oct 2020, Bill Cole wrote:

On 13 Oct 2020, at 15:02, Fred Morris wrote:


 Hello. Real example of someone with this setup, and all records for the
 FQDNs in question, or it didn't happen.


Waving at Fred...

billmail.scconsult.com. 10800   IN  MX  0 clues.scconsult.com.
billmail.scconsult.com. 10800   IN  MX  10 grumpy.scconsult.com.
scconsult.com.  86400   IN  MX  10 sc1.scconsult.com.
scconsult.com.  86400   IN  MX  1 toaster.scconsult.com.


Perfect, thanks! billmail.scconsult.com is not delegated from 
scconsult.com (has no SOA or NS), and sccconsult.com is delegated from 
.com (of course), with SOA and NS.


Bonus points: billmail has SPF.

(I'll assume that it works, since you're subscribed from 
@billmail.scconsult.com. I probably wouldn't set it up that way.)


--

Fred

Re: Mail server without MX record.

[Bill Cole]

On 13 Oct 2020, at 15:02, Fred Morris wrote:

Hello. Real example of someone with this setup, and all records for 
the FQDNs in question, or it didn't happen.


Waving at Fred...

billmail.scconsult.com. 10800   IN  MX  0 clues.scconsult.com.
billmail.scconsult.com. 10800   IN  MX  10 grumpy.scconsult.com.
scconsult.com.  86400   IN  MX  10 sc1.scconsult.com.
scconsult.com.  86400   IN  MX  1 toaster.scconsult.com.



On Tue, 13 Oct 2020, @lbutlr wrote:

On 13 Oct 2020, at 12:03, Fred Morris  wrote:
Notwithstanding, any "fully qualified domain name" (FQDN) can have 
email sent to it; typically only the FQDN immediately below the zone 
cut, and also the subject of SOA and NS records, has MX records.


Pretty sure it is prefect fine to have different MX records for 
subdomains.


example.com MX  10  mail.example.com.
foo MX  10  mail.sub1.example.com.
Bar MX  10  mail.sub2.example.com.

Universities used to often have different MX servers for different 
departments/machines, though now it seems they are using external 
services for MX (maybe lucky, I checked five and all were using 
google or outlook for MX).


Nothing here says that they haven't delegated e.g. foo.example.com.

Here, like this:

MariaDB [DNS]> SELECT name, type FROM Resource WHERE name IN (select 
name from Resource where name like '%.washington.edu.' and type = 
'MX') GROUP BY name, type ORDER BY name, type;

+---+--+
| name  | type |
+---+--+
| marge.cac.washington.edu. | A|
| marge.cac.washington.edu. | MX   |
| marge.cac.washington.edu. | NS   |
| math.washington.edu.  | MX   |
| math.washington.edu.  | NS   |
| staff.washington.edu. | MX   |
| staff.washington.edu. | NS   |
| u.washington.edu. | MX   |
| u.washington.edu. | NS   |
| www.atmos.washington.edu. | A|
| www.atmos.washington.edu. | MX   |
| www.atmos.washington.edu. | NS   |
+---+--+

--

Fred Morris



--
Bill Cole
b...@scconsult.com or billc...@apache.org
(AKA @grumpybozo and many *@billmail.scconsult.com addresses)
Not Currently Available For Hire

Re: Mail server without MX record.

[Ron Wheeler]

You want an MX record.
Why would you not want an MX record? What is the downside?

Where is your dns?



On 2020-10-13 11:04 a.m., Jason Long wrote:

I have an Internet domain name and a Linux server and I want to have an email server for send and 
receive emails. For example, if my domain is "example.net" then I want to have a 
"i...@example.net" address for send and receive emails from the Internet.








On Tuesday, October 13, 2020, 06:09:06 PM GMT+3:30, IL Ka 
 wrote:





What are you trying to achieve?

There are alot of scenarios where Postfix may be used:
* "Send only" email server for your website (to give your website ability to 
send emails). You never receive any emails from the outside.
* Forward only: it just accepts mails from your apps, and sends them via smart 
host (SMTP server of your provider). Some people run it on their laptops)
* Email hosting: users send and receive emails with your Postfix (as they do 
with Gmail, for example)
etc

It is important to choose a scenario, because if you only need to send emails 
from your website, then you do not need dovecot nor MX record and you even do 
not need to listen for incoming connections to the public port, but you may 
need DKIM and SPF.

In the "forward only via smart host" scenario you need almost nothing: no MX, 
no SPF/DKIM, no public port.
If you want to receive emails, then having an MX record is a good idea.
You would also need to listen public port for incoming connections, and may be 
one more port for clients (465 or 587)






On Tue, Oct 13, 2020 at 5:19 PM Jason Long  wrote:

Thank you for all of your messages.
With that tutorial, which record or port is needed?






On Tuesday, October 13, 2020, 04:31:34 PM GMT+3:30, Wietse Venema 
 wrote:





Jason Long:


Hello,
Can I use Postfix without MX record? I installed Postfix and?Dovecot
via "https://wiki.centos.org/HowTos/postfix; tutorial and I want
to know can I use it without MX record?


The SMTP standard (RFC 2821) does not *require* MX records. Some
uninformed mail operators may require one, but those are rare.

     Wietse




--
Ron Wheeler
Artifact Software
438-345-3369
rwhee...@artifact-software.com

Re: Mail server without MX record.

[IL Ka]

>1- Each domain can have a MX record?
If you want to receive email for this domain then yes, you should have an
MX record for it. Without it  "A" record will be used, but it is better to
have MX.


>2- If a company need multi MX record then it must have multi DNS server
too?
You can have multiple MX records with different priorities. Sender's MTA
will try first one first.
Number of DNS servers doesn't affect the number of MX records: in most
cases all public servers must have the same records.

>3- Other methods like forwarding need MX record too?
No, if you only want to send email, you are not required to have an MX
record. Some MTAs may decline messages from domains without of MX, but most
of them accept such mails.
But if you have no MX, then you can't get replies and non delivery reports.

There are some books about Postfix: "The book of Postfix", "Postfix: The
Definitive Guide". It may be a good idea to read some of them: they cover
how postfix works with DNS and MX.



On Tue, Oct 13, 2020 at 10:15 PM Jason Long  wrote:

> I'm really thankful for all information and help.
> Excuse me, I have some questions and I'm thankful if anyone answer to them
> by number:
> 1- Each domain can have a MX record?
> 2- If a company need multi MX record then it must have multi DNS server
> too?
> 3- Other methods like forwarding need MX record too?
>
> Thank you.
>
>
> Sent from Yahoo Mail on Android
> 
>
> On Tue, Oct 13, 2020 at 10:12 PM, @lbutlr
>  wrote:
> On 13 Oct 2020, at 12:03, Fred Morris  wrote:
>
> > Notwithstanding, any "fully qualified domain name" (FQDN) can have email
> sent to it; typically only the FQDN immediately below the zone cut, and
> also the subject of SOA and NS records, has MX records.
>
>
> Pretty sure it is prefect fine to have different MX records for subdomains.
>
> example.comMX10mail.example.com.
> fooMX10mail.sub1.example.com.
> BarMX10mail.sub2.example.com.
>
> Universities used to often have different MX servers for different
> departments/machines, though now it seems they are using external services
> for MX (maybe lucky, I checked five and all were using google or outlook
> for MX).
>
> --
> "Are you pondering what I'm pondering?"
> "I think so, Brain, but Tuesday Weld isn't a complete sentence."
>
>

Re: Mail server without MX record.

[Jason Long]

I'm really thankful for all information and help.Excuse me, I have some 
questions and I'm thankful if anyone answer to them by number:1- Each domain 
can have a MX record?2- If a company need multi MX record then it must have 
multi DNS server too?3- Other methods like forwarding need MX record too?
Thank you.

Sent from Yahoo Mail on Android 
 
  On Tue, Oct 13, 2020 at 10:12 PM, @lbutlr wrote:   On 13 
Oct 2020, at 12:03, Fred Morris  wrote:
> Notwithstanding, any "fully qualified domain name" (FQDN) can have email sent 
> to it; typically only the FQDN immediately below the zone cut, and also the 
> subject of SOA and NS records, has MX records.

Pretty sure it is prefect fine to have different MX records for subdomains.

example.com    MX    10    mail.example.com.
foo        MX    10    mail.sub1.example.com.
Bar        MX    10    mail.sub2.example.com.

Universities used to often have different MX servers for different 
departments/machines, though now it seems they are using external services for 
MX (maybe lucky, I checked five and all were using google or outlook for MX).

-- 
"Are you pondering what I'm pondering?"
"I think so, Brain, but Tuesday Weld isn't a complete sentence."
  

Re: Mail server without MX record.

[Fred Morris]

Hello. Real example of someone with this setup, and all records for the 
FQDNs in question, or it didn't happen.


On Tue, 13 Oct 2020, @lbutlr wrote:

On 13 Oct 2020, at 12:03, Fred Morris  wrote:
Notwithstanding, any "fully qualified domain name" (FQDN) can have 
email sent to it; typically only the FQDN immediately below the zone 
cut, and also the subject of SOA and NS records, has MX records.


Pretty sure it is prefect fine to have different MX records for subdomains.

example.com MX  10  mail.example.com.
foo MX  10  mail.sub1.example.com.
Bar MX  10  mail.sub2.example.com.

Universities used to often have different MX servers for different 
departments/machines, though now it seems they are using external 
services for MX (maybe lucky, I checked five and all were using google 
or outlook for MX).


Nothing here says that they haven't delegated e.g. foo.example.com.

Here, like this:

MariaDB [DNS]> SELECT name, type FROM Resource WHERE name IN (select name 
from Resource where name like '%.washington.edu.' and type = 'MX') GROUP 
BY name, type ORDER BY name, type;

+---+--+
| name  | type |
+---+--+
| marge.cac.washington.edu. | A|
| marge.cac.washington.edu. | MX   |
| marge.cac.washington.edu. | NS   |
| math.washington.edu.  | MX   |
| math.washington.edu.  | NS   |
| staff.washington.edu. | MX   |
| staff.washington.edu. | NS   |
| u.washington.edu. | MX   |
| u.washington.edu. | NS   |
| www.atmos.washington.edu. | A|
| www.atmos.washington.edu. | MX   |
| www.atmos.washington.edu. | NS   |
+---+--+

--

Fred Morris

Re: Mail server without MX record.

[@lbutlr]

On 13 Oct 2020, at 12:03, Fred Morris  wrote:
> Notwithstanding, any "fully qualified domain name" (FQDN) can have email sent 
> to it; typically only the FQDN immediately below the zone cut, and also the 
> subject of SOA and NS records, has MX records.

Pretty sure it is prefect fine to have different MX records for subdomains.

example.com MX  10  mail.example.com.
foo MX  10  mail.sub1.example.com.
Bar MX  10  mail.sub2.example.com.

Universities used to often have different MX servers for different 
departments/machines, though now it seems they are using external services for 
MX (maybe lucky, I checked five and all were using google or outlook for MX).

-- 
"Are you pondering what I'm pondering?"
"I think so, Brain, but Tuesday Weld isn't a complete sentence."

Re: Mail server without MX record.

[Fred Morris]

Notwithstanding, any "fully qualified domain name" (FQDN) can have email 
sent to it; typically only the FQDN immediately below the zone cut, and 
also the subject of SOA and NS records, has MX records.


But any other FQDN in the zone which has an A record should be 
deliverable, if it's routable and accepting traffic from the source. If 
you have joe.example.com (undelegated) and it has an A or  record and 
traffic from the sender can be routed to it nothing in mail or DNS 
prevents delivery to it, although senders may choose not to send to it 
based on local policy considerations.


On Tue, 13 Oct 2020, IL Ka wrote:


Date: Tue, 13 Oct 2020 19:06:05 +0300
From: IL Ka 
To: Jason Long 
Cc: Postfix users , "@lbutlr" 
Subject: Re: Mail server without MX record.


DNS server have another MX record for other mail server.

Then all mail to your domain will go to that mail server. No way to change
it. This is how SMTP works:

If one or more MX RRs are found for a given name, SMTP systems MUST
NOT utilize any A RRs

https://tools.ietf.org/html/rfc2821#section-5

You need to contact the DNS administrator. You would need DNS anyway,
because serious MTAs need SPF and DKIM: both are DNS records.

On Tue, Oct 13, 2020 at 6:53 PM Jason Long  wrote:


I can't have MX record because the DNS server have another MX record for
other mail server.
I'm thankful if anyone tell me how can I solve my problem without MX
record. Is t possible with A record?


See top post.


[...]
On 13 Oct 2020, at 09:45, Bernardo Reino  wrote:


On Tue, 13 Oct 2020, Jason Long wrote:

I have an Internet domain name and a Linux server and I want to have 
an email server for send and receive emails. For example, if my 
domain is "example.net" then I want to have a "i...@example.net"

address for send and receive emails from the Internet.


If you have MX for example.net then it overrides A record for example.net 
domain name. But please remember that "domain name" in DNS is a 
mathematical concept, it does not mean "a domain name having an SOA or 
equivalently immediately below a zone cut".


--

Fred Morris

Re: Mail server without MX record.

[Chris Green]

On Tue, Oct 13, 2020 at 04:42:31PM +, Richard wrote:
> 
> 
> > Date: Tuesday, October 13, 2020 15:52:41 +
> > From: Jason Long 
> >
> > I can't have MX record because the DNS server have another MX
> > record for other mail server. I'm thankful if anyone tell me how
> > can I solve my problem without MX record. Is t possible with A
> > record?
> 
> Either you misstated the issue or someone has a poor understanding of
> DNS.
> 
> You might want to step back and get a more complete understanding of
> the workings of mail and DNS. Without that, simply following
> "cookbooks" will likely not get you where you want to be.
> 
I think it *may* be that the OP doesn't realise he can/should change
the MX record.  If you have a domain hosted at your average hosting
service the A record gets to point at whatever you need (home system,
virtual host, whatever) but the MX record is left pointing at the
hosting company's mail servers.  It's quite a rarity in the general
run of things that the MX record gets changed.


-- 
Chris Green

Re: Mail server without MX record.

[Richard]

> Date: Tuesday, October 13, 2020 15:52:41 +
> From: Jason Long 
>
> I can't have MX record because the DNS server have another MX
> record for other mail server. I'm thankful if anyone tell me how
> can I solve my problem without MX record. Is t possible with A
> record?

Either you misstated the issue or someone has a poor understanding of
DNS.

You might want to step back and get a more complete understanding of
the workings of mail and DNS. Without that, simply following
"cookbooks" will likely not get you where you want to be.

[by the way, while I don't think that this list is hardcore on
posting order, most technical lists frown on top posting.]

Re: Mail server without MX record.

[IL Ka]

> DNS server have another MX record for other mail server.
Then all mail to your domain will go to that mail server. No way to change
it. This is how SMTP works:


If one or more MX RRs are found for a given name, SMTP systems MUST
NOT utilize any A RRs


https://tools.ietf.org/html/rfc2821#section-5



You need to contact the DNS administrator. You would need DNS anyway,
because serious MTAs need SPF and DKIM: both are DNS records.


On Tue, Oct 13, 2020 at 6:53 PM Jason Long  wrote:

> I can't have MX record because the DNS server have another MX record for
> other mail server.
> I'm thankful if anyone tell me how can I solve my problem without MX
> record. Is t possible with A record?
>
>
>
>
>
>
> On Tuesday, October 13, 2020, 07:19:56 PM GMT+3:30, @lbutlr <
> krem...@kreme.com> wrote:
>
>
>
>
>
> On 13 Oct 2020, at 09:45, Bernardo Reino  wrote:
>
> > On Tue, 13 Oct 2020, Jason Long wrote:
> >
> >> I have an Internet domain name and a Linux server and I want to have an
> email server for send and receive emails. For example, if my domain is "
> example.net" then I want to have a "i...@example.net" address for send
> and receive emails from the Internet.
> >
> > But then why no MX record?
> >
> > It's absolutely common, normal and expected to have an MX record so that
> other MTAs know where you actually want to have your mail delivered.
>
>
> It is also somewhat suspicious to have a mail server without an MX record.
> Sure, it’s ALLOWED, but it’s still weird.
>
> --
> 99 percent of police give the rest a bad name.
>

Re: Mail server without MX record.

[Jason Long]

I can't have MX record because the DNS server have another MX record for other 
mail server.
I'm thankful if anyone tell me how can I solve my problem without MX record. Is 
t possible with A record?






On Tuesday, October 13, 2020, 07:19:56 PM GMT+3:30, @lbutlr  
wrote: 





On 13 Oct 2020, at 09:45, Bernardo Reino  wrote:

> On Tue, 13 Oct 2020, Jason Long wrote:
> 
>> I have an Internet domain name and a Linux server and I want to have an 
>> email server for send and receive emails. For example, if my domain is 
>> "example.net" then I want to have a "i...@example.net" address for send and 
>> receive emails from the Internet.
> 
> But then why no MX record?
> 
> It's absolutely common, normal and expected to have an MX record so that 
> other MTAs know where you actually want to have your mail delivered.


It is also somewhat suspicious to have a mail server without an MX record. 
Sure, it’s ALLOWED, but it’s still weird.

-- 
99 percent of police give the rest a bad name.

Re: Mail server without MX record.

[@lbutlr]

On 13 Oct 2020, at 09:45, Bernardo Reino  wrote:
> On Tue, 13 Oct 2020, Jason Long wrote:
> 
>> I have an Internet domain name and a Linux server and I want to have an 
>> email server for send and receive emails. For example, if my domain is 
>> "example.net" then I want to have a "i...@example.net" address for send and 
>> receive emails from the Internet.
> 
> But then why no MX record?
> 
> It's absolutely common, normal and expected to have an MX record so that 
> other MTAs know where you actually want to have your mail delivered.

It is also somewhat suspicious to have a mail server without an MX record. 
Sure, it’s ALLOWED, but it’s still weird.

-- 
99 percent of police give the rest a bad name.

Re: Mail server without MX record.

[Bernardo Reino]

On Tue, 13 Oct 2020, Jason Long wrote:

I have an Internet domain name and a Linux server and I want to have an 
email server for send and receive emails. For example, if my domain is 
"example.net" then I want to have a "i...@example.net" address for send 
and receive emails from the Internet.


But then why no MX record?

It's absolutely common, normal and expected to have an MX record so that 
other MTAs know where you actually want to have your mail delivered.


I'd advise you to first read about postfix (i.e. the manual), rather than 
some random outdated tutorials (do you use the same nickname at the Debian 
forum? :)


Cheers.


On Tuesday, October 13, 2020, 06:09:06 PM GMT+3:30, IL Ka 
 wrote:





What are you trying to achieve?

There are alot of scenarios where Postfix may be used:
* "Send only" email server for your website (to give your website ability to 
send emails). You never receive any emails from the outside.
* Forward only: it just accepts mails from your apps, and sends them via smart 
host (SMTP server of your provider). Some people run it on their laptops)
* Email hosting: users send and receive emails with your Postfix (as they do 
with Gmail, for example)
etc

It is important to choose a scenario, because if you only need to send emails 
from your website, then you do not need dovecot nor MX record and you even do 
not need to listen for incoming connections to the public port, but you may 
need DKIM and SPF.

In the "forward only via smart host" scenario you need almost nothing: no MX, 
no SPF/DKIM, no public port.
If you want to receive emails, then having an MX record is a good idea. 
You would also need to listen public port for incoming connections, and may be 
one more port for clients (465 or 587)






On Tue, Oct 13, 2020 at 5:19 PM Jason Long  wrote:

Thank you for all of your messages.
With that tutorial, which record or port is needed? 






On Tuesday, October 13, 2020, 04:31:34 PM GMT+3:30, Wietse Venema 
 wrote:





Jason Long:


Hello,
Can I use Postfix without MX record? I installed Postfix and?Dovecot
via "https://wiki.centos.org/HowTos/postfix; tutorial and I want
to know can I use it without MX record?



The SMTP standard (RFC 2821) does not *require* MX records. Some
uninformed mail operators may require one, but those are rare.

    Wietse

Re: Mail server without MX record.

[Jason Long]

I have an Internet domain name and a Linux server and I want to have an email 
server for send and receive emails. For example, if my domain is "example.net" 
then I want to have a "i...@example.net" address for send and receive emails 
from the Internet.








On Tuesday, October 13, 2020, 06:09:06 PM GMT+3:30, IL Ka 
 wrote: 





What are you trying to achieve?

There are alot of scenarios where Postfix may be used:
* "Send only" email server for your website (to give your website ability to 
send emails). You never receive any emails from the outside.
* Forward only: it just accepts mails from your apps, and sends them via smart 
host (SMTP server of your provider). Some people run it on their laptops)
* Email hosting: users send and receive emails with your Postfix (as they do 
with Gmail, for example)
etc

It is important to choose a scenario, because if you only need to send emails 
from your website, then you do not need dovecot nor MX record and you even do 
not need to listen for incoming connections to the public port, but you may 
need DKIM and SPF.

In the "forward only via smart host" scenario you need almost nothing: no MX, 
no SPF/DKIM, no public port.
If you want to receive emails, then having an MX record is a good idea. 
You would also need to listen public port for incoming connections, and may be 
one more port for clients (465 or 587)






On Tue, Oct 13, 2020 at 5:19 PM Jason Long  wrote:
> Thank you for all of your messages.
> With that tutorial, which record or port is needed? 
> 
> 
> 
> 
> 
> 
> On Tuesday, October 13, 2020, 04:31:34 PM GMT+3:30, Wietse Venema 
>  wrote: 
> 
> 
> 
> 
> 
> Jason Long:
> 
>> Hello,
>> Can I use Postfix without MX record? I installed Postfix and?Dovecot
>> via "https://wiki.centos.org/HowTos/postfix; tutorial and I want
>> to know can I use it without MX record?
> 
> 
> The SMTP standard (RFC 2821) does not *require* MX records. Some
> uninformed mail operators may require one, but those are rare.
> 
>     Wietse
> 
> 

Re: Mail server without MX record.

[IL Ka]

What are you trying to achieve?

There are alot of scenarios where Postfix may be used:
* "Send only" email server for your website (to give your website ability
to send emails). You never receive any emails from the outside.
* Forward only: it just accepts mails from your apps, and sends them via
smart host (SMTP server of your provider). Some people run it on their
laptops)
* Email hosting: users send and receive emails with your Postfix (as they
do with Gmail, for example)
etc

It is important to choose a scenario, because if you only need to send
emails from your website, then you do not need dovecot nor MX record and
you even do not need to listen for incoming connections to the public port,
but you may need DKIM and SPF.

In the "forward only via smart host" scenario you need almost nothing: no
MX, no SPF/DKIM, no public port.
If you want to receive emails, then having an MX record is a good idea.
You would also need to listen public port for incoming connections, and may
be one more port for clients (465 or 587)






On Tue, Oct 13, 2020 at 5:19 PM Jason Long  wrote:

> Thank you for all of your messages.
> With that tutorial, which record or port is needed?
>
>
>
>
>
>
> On Tuesday, October 13, 2020, 04:31:34 PM GMT+3:30, Wietse Venema <
> wie...@porcupine.org> wrote:
>
>
>
>
>
> Jason Long:
>
> > Hello,
> > Can I use Postfix without MX record? I installed Postfix and?Dovecot
> > via "https://wiki.centos.org/HowTos/postfix; tutorial and I want
> > to know can I use it without MX record?
>
>
> The SMTP standard (RFC 2821) does not *require* MX records. Some
> uninformed mail operators may require one, but those are rare.
>
> Wietse
>
>

Re: Mail server without MX record.

[Jason Long]

Thank you for all of your messages.
With that tutorial, which record or port is needed? 






On Tuesday, October 13, 2020, 04:31:34 PM GMT+3:30, Wietse Venema 
 wrote: 





Jason Long:

> Hello,
> Can I use Postfix without MX record? I installed Postfix and?Dovecot
> via "https://wiki.centos.org/HowTos/postfix; tutorial and I want
> to know can I use it without MX record?


The SMTP standard (RFC 2821) does not *require* MX records. Some
uninformed mail operators may require one, but those are rare.

    Wietse

Re: Mail server without MX record.

[Bill Cole]

On 13 Oct 2020, at 8:09, Jason Long wrote:


Hello,
Can I use Postfix without MX record? I installed Postfix and Dovecot 
via "https://wiki.centos.org/HowTos/postfix; tutorial and I want to 
know can I use it without MX record?


That is entirely dependent on what you intend to use Postfix for.

If you have a domain name for which you want to receive mail directly 
from the world at large, it must have either an A record that resolves 
to the address of your Postfix server or a MX record that points to a 
name that has an A record that resolves to the address of your Postfix 
server.



--
Bill Cole
b...@scconsult.com or billc...@apache.org
(AKA @grumpybozo and many *@billmail.scconsult.com addresses)
Not Currently Available For Hire

Re: Mail server without MX record.

[Wietse Venema]

Jason Long:
> Hello,
> Can I use Postfix without MX record? I installed Postfix and?Dovecot
> via "https://wiki.centos.org/HowTos/postfix; tutorial and I want
> to know can I use it without MX record?

The SMTP standard (RFC 2821) does not *require* MX records. Some
uninformed mail operators may require one, but those are rare.

Wietse

Re: Mail server without MX record.

[Richard]

> Date: Tuesday, October 13, 2020 12:09:28 +
> From: Jason Long 
>
> Hello,
> Can I use Postfix without MX record? I installed Postfix
> and Dovecot via "https://wiki.centos.org/HowTos/postfix; tutorial
> and I want to know can I use it without MX record?

Yes. Some mail sites, incorrectly, think that one has to have an
MX-record for a site to be legit, but major ones know better. An
MX-record is related to inbound routing/deliverability, and not
specific to the MTA one is using.

You do need an A-, and for successful outbound deliverability, a
matching Rdns record. As noted in an earlier message chain, there is
a list of other things, e.g., SPF, DKIM, DMARC records, etc., that
will help in deliverability.

By the way, the documentation that you pointed to specifies that it
is written for Centos-5. As Centos-6 is EOL next month, C5 and
earlier are already EOL. So you should be using at least Centos-7,
and relevant documentation. Something in one of your messages
yesterday indicated that you were likely using Centos-6 or earlier.

Re: Mail server without MX record.

[A. Schulze]

Am 13.10.20 um 14:09 schrieb Jason Long:
> I want to know can I use it without MX record?
A records are used by default if no MX is available
That's nothing postfix specific - it's an RFC requirement for any MTA

Andreas