Re: [mailop] Cannot send messages to Google Mail users

[Matus UHLAR - fantomas via mailop]

On 24.04.24 17:00, Simon Branch via mailop wrote:

  Thank you everyone for your input.

  After reading the various comments, I decided to try creating a connector
  in 365, specifically for emails going to the Gmail domain.

  Funnily enough, the emails are now delivered to Google's servers, albeit
  the messages end up in users spam folders, as opposed to their inboxes.

  Would this be an SPF issue or something else?


I guess it is exactly the same issue, just your rating was increased from 
reject to mark-as-spam.


Did you configure the connector already? If not, it probably is not needed.

You just need to find out if someone spammed from your domain, either from 
365 or from other servers.

(or if someone tried to bomb google from your domain).


  This afternoon I opened another case with Microsoft and explained what has
  taken place and about the connector.

  They have admitted that they are having issues with messages not being
  delivered to Google, after spending the past week saying the opposite!


I thinks many 365 IP addresses got to some blocklists in the not so distant 
past, but I don't know if this caused issues with google.



--
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Warning: I wish NOT to receive e-mail advertising to this address.
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Re: [mailop] Cannot send messages to Google Mail users

[Simon Branch via mailop]

Firstly,Thank you everyone for your input.After reading the various comments, I decided to try creating a connector in 365, specifically for emails going to the Gmail domain.Funnily enough, the emails are now delivered to Google's servers, albeit the messages end up in users spam folders, as opposed to their inboxes.Would this be an SPF issue or something else?This afternoon I opened another case with Microsoft and explained what has taken place and about the connector.They have admitted that they are having issues with messages not being delivered to Google, after spending the past week saying the opposite!Thanks,Simon

	
  
   
		
			
			

	
		 
		
		
			
	
		 
		
		
			

	


	 



			
		

		
			

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-Original Message-From: Al Iverson  Sent: Wednesday, April 24, 2024 4:05 PMTo: Mailop Mailing List Subject: Re: [mailop] Cannot send messages to Google Mail usersIs disabling IPv6 an option here? A prior poster suggested as such, but I don't know if that was just a general suggestion or if that's actually possible in O365 settings.But if you can  yes, try sending outbound mail only via IPv4. A "well known secret" is that Gmail filters mail from IPv6 connections more harshly than IPv4. Maybe less than they once did, and certainly you could question if it's fair or not, but I saw clear evidence of it in the past. I personally have IPv6 disabled on my MTA because of it.Also make sure your DKIM is set up as YOU and not just as the default *.onmicrosoft.com that Microsoft sticks on there for those who aren't fully configured.If you want folks to look at headers and offer up additional suggestions, run a test using https://aboutmy.email and share the results link here. I'll take a look and advise, and I imagine others will, too.Cheers,Al Iverson-- Al Iverson // 312-725-0130 // Chicagohttp://www.spamresource.com // Deliverability http://www.aliverson.com // All about me https://xnnd.com/calendar // Book my calendar___
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Re: [mailop] Cannot send messages to Google Mail users

[Mark Alley via mailop]

On 4/24/2024 10:04 AM, Al Iverson via mailop wrote:

Is disabling IPv6 an option here? A prior poster suggested as such,
but I don't know if that was just a general suggestion or if that's
actually possible in O365 settings.

But if you can  yes, try sending outbound mail only via IPv4. A
"well known secret" is that Gmail filters mail from IPv6 connections
more harshly than IPv4. Maybe less than they once did, and certainly
you could question if it's fair or not, but I saw clear evidence of it
in the past. I personally have IPv6 disabled on my MTA because of it.

Also make sure your DKIM is set up as YOU and not just as the default
*.onmicrosoft.com that Microsoft sticks on there for those who aren't
fully configured.

If you want folks to look at headers and offer up additional
suggestions, run a test usinghttps://aboutmy.email  and share the
results link here. I'll take a look and advise, and I imagine others
will, too.

Cheers,
Al Iverson


They'd have to request it be disabled from Microsoft support. In the 
past, someone would have had to request it be enabled explicitly for it 
to be on in their Exchange Online tenant, because IPv6 is not enabled by 
default to my knowledge.


- Mark Alley
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Re: [mailop] Cannot send messages to Google Mail users

[Al Iverson via mailop]

Is disabling IPv6 an option here? A prior poster suggested as such,
but I don't know if that was just a general suggestion or if that's
actually possible in O365 settings.

But if you can  yes, try sending outbound mail only via IPv4. A
"well known secret" is that Gmail filters mail from IPv6 connections
more harshly than IPv4. Maybe less than they once did, and certainly
you could question if it's fair or not, but I saw clear evidence of it
in the past. I personally have IPv6 disabled on my MTA because of it.

Also make sure your DKIM is set up as YOU and not just as the default
*.onmicrosoft.com that Microsoft sticks on there for those who aren't
fully configured.

If you want folks to look at headers and offer up additional
suggestions, run a test using https://aboutmy.email and share the
results link here. I'll take a look and advise, and I imagine others
will, too.

Cheers,
Al Iverson



-- 

Al Iverson // 312-725-0130 // Chicago
http://www.spamresource.com // Deliverability
http://www.aliverson.com // All about me
https://xnnd.com/calendar // Book my calendar
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Re: [mailop] Cannot send messages to Google Mail users

[Mark Alley via mailop]

I've also seen Google provide this error when a domain had a
spammer/phisher attempt to spoof said domain several hundred thousand
times. Since Google saw their domain in the RFC5321.Mailfrom, even though
the messages weren't authenticated and were rejected as per their DMARC
policy, the domain's mere existence in the RFC5321.Mailfrom for SPF was
enough to tank their reputation with Google to abysmal levels.

I'd suggest checking their DMARC reporting historical data (if available)
to see if this potentially occurred recently.

- Mark Alley


Sent from mobile, please excuse any typos.

On Wed, Apr 24, 2024, 5:09 AM Matus UHLAR - fantomas via mailop <
mailop@mailop.org> wrote:

> On 24.04.24 07:28, Simon Branch via mailop wrote:
> > For the past 2 weeks, we have been unable to send mails to any gmail
> users,
> > nor any email domains hosted on Google's mail servers.  We are using
> > Microsoft 365.
>
> So I assume you send your mail through microsoft/outlook servers, you
> can't
> your outgoing IP, and don't need to change it.
>
> > Every time we attempt to send a message, we get the following
> bounce-back:
> >
> > 550 5.7.350 Remote server returned message detected as spam -> 550 5.7.1
> [2a01:111:f403:261b::700 19] Gmail has detected that this message;is likely
> suspicious due to the very low reputation of the sending;domain.
> > To best protect our users from spam, the message has been;blocked. For
> more information, go to; https://support.google.com/mail/answer/188131
> im8-20020a056214246800b00696b2e6b32asi14453219qvb.337 - gsmtp
> >
> > I have been in touch with Microsoft 365 support and they have double
> > checked our SPF / DMARC / DKIM records and all are correct.
> >
> > The only advice Microsoft will give is to speak to Google.
> >
> > I have filled out one of Googles email cases, explaining that our DNS
> > records are set up correctly and we are not spamming.
> >
> > Unfortunately, we have had no reply after a week.
> >
> > Is there anything we can do to help resolve the issue?
>
> I had similar problem with out customers' domain a few months ago.
> The problem happened because of spamming from that domain (hijacked
> account), while SPF and DKIM were correct.
>
> It took about month until mail started working.
>
> Make sure nobody did spam/mailbomb from your domain while having matching
> SPF/DKIM.  I guess that could include forwarding of spam messages or
> creating mail loop etc.  I also guess you signed into google postmaster
> tools and configured your domain.
>
> https://postmaster.google.com/
>
> check SPF/DKIM records if they don't allow sending authenticated mail from
> other places.
>
> --
> Matus UHLAR - fantomas, uh...@fantomas.sk ; http://www.fantomas.sk/
> Warning: I wish NOT to receive e-mail advertising to this address.
> Varovanie: na tuto adresu chcem NEDOSTAVAT akukolvek reklamnu postu.
> Fighting for peace is like fucking for virginity...
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Re: [mailop] Cannot send messages to Google Mail users

[Stuart Henderson via mailop]

On 2024/04/24 12:04, Matus UHLAR - fantomas via mailop wrote:
> Make sure nobody did spam/mailbomb from your domain while having matching
> SPF/DKIM.  I guess that could include forwarding of spam messages or
> creating mail loop etc.

AFAIK forwarding mail into gmail is generally not good for your
reputation scores. People that want that are probably better off
having gmail pull over pop3 instead.

>  I also guess you signed into google postmaster
> tools and configured your domain.
> 
> https://postmaster.google.com/

That seems rather hit and miss whether it will show you anything. Works
fine on my personal domain with fairly low send rates, but after a few
months it's still "No data to display at present. Please come back
later" for a few work ones with slightly higher (but still not really
high) rates.

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Re: [mailop] Cannot send messages to Google Mail users

[Matus UHLAR - fantomas via mailop]

On 24.04.24 07:28, Simon Branch via mailop wrote:
For the past 2 weeks, we have been unable to send mails to any gmail users, 
nor any email domains hosted on Google's mail servers.  We are using 
Microsoft 365.


So I assume you send your mail through microsoft/outlook servers, you can't 
your outgoing IP, and don't need to change it.



Every time we attempt to send a message, we get the following bounce-back:

550 5.7.350 Remote server returned message detected as spam -> 550 5.7.1 
[2a01:111:f403:261b::700 19] Gmail has detected that this message;is likely 
suspicious due to the very low reputation of the sending;domain.
To best protect our users from spam, the message has been;blocked. For more 
information, go to; https://support.google.com/mail/answer/188131 
im8-20020a056214246800b00696b2e6b32asi14453219qvb.337 - gsmtp

I have been in touch with Microsoft 365 support and they have double 
checked our SPF / DMARC / DKIM records and all are correct.


The only advice Microsoft will give is to speak to Google.

I have filled out one of Googles email cases, explaining that our DNS 
records are set up correctly and we are not spamming.


Unfortunately, we have had no reply after a week.

Is there anything we can do to help resolve the issue?


I had similar problem with out customers' domain a few months ago.
The problem happened because of spamming from that domain (hijacked 
account), while SPF and DKIM were correct.


It took about month until mail started working.

Make sure nobody did spam/mailbomb from your domain while having matching 
SPF/DKIM.  I guess that could include forwarding of spam messages or 
creating mail loop etc.  I also guess you signed into google postmaster 
tools and configured your domain.


https://postmaster.google.com/

check SPF/DKIM records if they don't allow sending authenticated mail from 
other places.


--
Matus UHLAR - fantomas, uh...@fantomas.sk ; http://www.fantomas.sk/
Warning: I wish NOT to receive e-mail advertising to this address.
Varovanie: na tuto adresu chcem NEDOSTAVAT akukolvek reklamnu postu.
Fighting for peace is like fucking for virginity...
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Re: [mailop] Cannot send messages to Google Mail users

[Florian Effenberger via mailop]

Hi,

Marco Moock via mailop wrote on 24.04.24 at 10:41:

That is fine, the host has 2 addresses attached.
Both have a PTR.

I don't see a DNS issue.


I just had a look at one of my friend's MX and can confirm that the PTR 
was correct there as well - but disabling IPv6 interestingly helped to 
avoid the rejection...


Florian
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Re: [mailop] Cannot send messages to Google Mail users

[Marco Moock via mailop]

Am 24.04.2024 um 10:08:53 Uhr schrieb Marco Davids via mailop:

> However, the IPv6-address in the error below resolves to two names:
> 
> ;; ANSWER SECTION:
> 0.0.7.0.0.0.0.0.0.0.0.0.0.0.0.0.b.1.6.2.3.0.4.f.1.1.1.0.1.0.a.2.ip6.arpa. 
> 3165 IN PTR mail-cwxgbr01on20700.outbound.protection.outlook.com.

The IP resolves to one domain (PTR).

> ;; ANSWER SECTION:
> mail-cwxgbr01on20700.outbound.protection.outlook.com. 24 IN  
> 2a01:111:f403:707f::700
> mail-cwxgbr01on20700.outbound.protection.outlook.com. 24 IN  
> 2a01:111:f403:261b::700

That is fine, the host has 2 addresses attached.
Both have a PTR.

I don't see a DNS issue.

-- 
Gruß
Marco

Send unsolicited bulk mail to 1713946133mu...@cartoonies.org
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Re: [mailop] Cannot send messages to Google Mail users

[Marco Davids via mailop]

Not sure if this helps, but Gmail requires forward and reverse DNS for 
IPv6 to match.


Like this (example is from our own setup):

;; ANSWER SECTION:
e.1.7.0.0.0.0.0.0.0.0.0.0.0.0.0.a.1.e.7.0.0.4.f.1.1.1.0.1.0.a.2.ip6.arpa. 
3379 IN PTR mail-db8eur05on2071e.outbound.protection.outlook.com.


;; ANSWER SECTION:
mail-db8eur05on2071e.outbound.protection.outlook.com. 76 IN  
2a01:111:f400:7e1a::71e


However, the IPv6-address in the error below resolves to two names:

;; ANSWER SECTION:
0.0.7.0.0.0.0.0.0.0.0.0.0.0.0.0.b.1.6.2.3.0.4.f.1.1.1.0.1.0.a.2.ip6.arpa. 
3165 IN PTR mail-cwxgbr01on20700.outbound.protection.outlook.com.


;; ANSWER SECTION:
mail-cwxgbr01on20700.outbound.protection.outlook.com. 24 IN  
2a01:111:f403:707f::700
mail-cwxgbr01on20700.outbound.protection.outlook.com. 24 IN  
2a01:111:f403:261b::700


If that is indeed an issue for Gmail, dan MS365 should perhaps fix this?

--
Marco


Op 24-04-2024 om 09:33 schreef Florian Effenberger via mailop:


Simon Branch via mailop wrote on 24.04.24 at 09:28:
/550 5.7.350 Remote server returned message detected as spam -> 550 
5.7.1 [2a01:111:f403:261b::700 19] Gmail has detected that this 
message;is likely suspicious due to the very low reputation of the 
sending;domain. /


/To best protect our users from spam, the message has been;blocked. 
For more information, go to; 
https://support.google.com/mail/answer/188131 
 
im8-20020a056214246800b00696b2e6b32asi14453219qvb.337 - gsmtp/


a friend of mine had a similar problem lately. DKIM, SPF, DMARC, PTR 
were all set up correctly, no blocklist entry.


He disabled IPv6 delivery to Google and could send his e-mails with 
IPv4, so "domain reputation" suggest something that might not be 
applicable, as the sending domain per se seemed fine.


I don't know how flexible you are in your configuration with MS365, but 
the error message suggests you connect to GMail via IPv6, so maybe the 
above helps.


Florian


smime.p7s
Description: S/MIME-cryptografische ondertekening
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Re: [mailop] Cannot send messages to Google Mail users

[Florian Effenberger via mailop]

Hello,

Simon Branch via mailop wrote on 24.04.24 at 09:28:
/550 5.7.350 Remote server returned message detected as spam -> 550 
5.7.1 [2a01:111:f403:261b::700 19] Gmail has detected that this 
message;is likely suspicious due to the very low reputation of the 
sending;domain. /


/To best protect our users from spam, the message has been;blocked. For 
more information, go to; https://support.google.com/mail/answer/188131 
 
im8-20020a056214246800b00696b2e6b32asi14453219qvb.337 - gsmtp/


a friend of mine had a similar problem lately. DKIM, SPF, DMARC, PTR 
were all set up correctly, no blocklist entry.


He disabled IPv6 delivery to Google and could send his e-mails with 
IPv4, so "domain reputation" suggest something that might not be 
applicable, as the sending domain per se seemed fine.


I don't know how flexible you are in your configuration with MS365, but 
the error message suggests you connect to GMail via IPv6, so maybe the 
above helps.


Florian
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