Re: [mailop] Google unsolicited mail rejected with 421

2024-03-19 Thread Brandon Long via mailop
Most likely the reasoning behind something like this is dkim replay
attacks, where a message with a single recipient is re-sent to a large
number of recipients.

Of course mailing lists should be exempted, the challenge is if you reply
to both the list and the person directly, the reply to the person didn't go
through the list and can't be easily exempted.  Oh, and you have to be
careful how you make the exemption since you don't want the dkim reply
spammers to figure it out and exempt themselves, there isn't a registry of
legitimate mailing lists.

Obviously if this is affecting a large number of folks as false positives,
it could use some tuning... but I think the set of rules like this started
years ago at this point, but new rules and tuning and just the general
dynamics of the system will change the performance and effect.

As for preferencing Google Groups, at least when I was on the team, Google
Groups went in through the same smtp-in door as any other mail, and was
treated the same as any other mail... in general, the only differences
there was that it is a known mailing list host and as a large one had some
special handling to differentiate between different groups... and this same
type of thing was used for most of the large mailing list operators that
the team was aware of.  Open source mailing lists were also usually handled
specially where possible, definitely out of proportion to their actual mail
volume or affected users.

At the time, debian mailing lists were also specially handled due to their
poor email hygiene practices, in particular their opposition to using SPF
because they didn't want to run a central MSA for people to use their
debian.org email addresses.

The issue with any special handling is that it adds tech debt to the
system, makes it more complicated, and the handling can become out of date
over time... I don't know if debian has started using SPF (a quick look
says no), or if they don't, whether the system still has any special
handling for them, since removing that special handling or having it break
probably wouldn't move the needle on any metrics for the system as a
whole.  I wouldn't be surprised if we still have yahooogroups.com listed as
a large scale mailing list system... even though it's gone or if
groups.io is listed since it's probably grown large enough that it could be.

Brandon

On Sun, Mar 17, 2024 at 6:04 AM Benny Pedersen via mailop 
wrote:

> Jaroslaw Rafa via mailop skrev den 2024-03-17 13:38:
> > Dnia 16.03.2024 o godz. 13:08:52 Benny Pedersen via mailop pisze:
> >>
> >> bingo its why its tempfailed, gmail should redesign how to handle
> >> maillists where message-id can come to inbound on gmail, should not
> >> count on message-id abuse counts
> >
> > Well... from Google's point of view, it seems like a pretty effective
> > mechanism to force people to move to *their* mailing list service,
> > instead
> > of running mailing list themselves...
> >
> > A monopoly wants to be a monopoly.
>
> sure any stupid user can forward mails that is received on maillist to
> there own private gmail account, more or less its this
>
> stop forwarding mails as maillist subscriber is better, in generic world
> is lots better when no mail is forwarded
>
> srs would not fix anything anyway
>
> setup forwarder with sasl client in mta to delivery to freemail provider
> solves it
>
>
>
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Re: [mailop] Google unsolicited mail rejected with 421

2024-03-17 Thread Benny Pedersen via mailop

Jaroslaw Rafa via mailop skrev den 2024-03-17 13:38:

Dnia 16.03.2024 o godz. 13:08:52 Benny Pedersen via mailop pisze:


bingo its why its tempfailed, gmail should redesign how to handle
maillists where message-id can come to inbound on gmail, should not
count on message-id abuse counts


Well... from Google's point of view, it seems like a pretty effective
mechanism to force people to move to *their* mailing list service, 
instead

of running mailing list themselves...

A monopoly wants to be a monopoly.


sure any stupid user can forward mails that is received on maillist to 
there own private gmail account, more or less its this


stop forwarding mails as maillist subscriber is better, in generic world 
is lots better when no mail is forwarded


srs would not fix anything anyway

setup forwarder with sasl client in mta to delivery to freemail provider 
solves it




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Re: [mailop] Google unsolicited mail rejected with 421

2024-03-17 Thread Jaroslaw Rafa via mailop
Dnia 16.03.2024 o godz. 13:08:52 Benny Pedersen via mailop pisze:
> 
> bingo its why its tempfailed, gmail should redesign how to handle
> maillists where message-id can come to inbound on gmail, should not
> count on message-id abuse counts

Well... from Google's point of view, it seems like a pretty effective
mechanism to force people to move to *their* mailing list service, instead
of running mailing list themselves...

A monopoly wants to be a monopoly.
-- 
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."
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Re: [mailop] Google unsolicited mail rejected with 421

2024-03-16 Thread Marco Moock via mailop
Am 16.03.2024 um 13:08:52 Uhr schrieb Benny Pedersen via mailop:

> Marco Moock via mailop skrev den 2024-03-16 12:46:
> > Am 14.03.2024 um 10:28:13 Uhr schrieb Julian Bradfield via mailop:
> >   
> >> Their latest daftness (latest in my noticing it, anyway) is
> >> rate-limiting on the basis of too many recipients for a single
> >> message-id, where "too many" varies from 6 to 30. You'd think
> >> they'd never heard of organization mailing lists.  
> > 
> > That seems to be the case here too.
> > If I reply to somebody a gmail directly (not to the list) it gets
> > through.  
> 
> bingo its why its tempfailed, gmail should redesign how to handle 
> maillists where message-id can come to inbound on gmail, should not 
> count on message-id abuse counts

The current situation is even worse when mailing list subscribers
forward their stuff to gmail. That will result in many, many
"unsolicited" mails because those servers will try it a few times
because of the tempfail.

A rather crappy solution by Google.


-- 
Gruß
Marco

Send spam to 1710590932mu...@cartoonies.org
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Re: [mailop] Google unsolicited mail rejected with 421

2024-03-16 Thread Benny Pedersen via mailop

Marco Moock via mailop skrev den 2024-03-16 12:46:

Am 14.03.2024 um 10:28:13 Uhr schrieb Julian Bradfield via mailop:


Their latest daftness (latest in my noticing it, anyway) is
rate-limiting on the basis of too many recipients for a single
message-id, where "too many" varies from 6 to 30. You'd think they'd
never heard of organization mailing lists.


That seems to be the case here too.
If I reply to somebody a gmail directly (not to the list) it gets
through.


bingo its why its tempfailed, gmail should redesign how to handle 
maillists where message-id can come to inbound on gmail, should not 
count on message-id abuse counts



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Re: [mailop] Google unsolicited mail rejected with 421

2024-03-16 Thread Marco Moock via mailop
Am 14.03.2024 um 10:28:13 Uhr schrieb Julian Bradfield via mailop:

> Their latest daftness (latest in my noticing it, anyway) is
> rate-limiting on the basis of too many recipients for a single
> message-id, where "too many" varies from 6 to 30. You'd think they'd
> never heard of organization mailing lists.

That seems to be the case here too.
If I reply to somebody a gmail directly (not to the list) it gets
through.

-- 
kind regards
Marco

Send spam to 1710408493mu...@cartoonies.org
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Re: [mailop] Google unsolicited mail rejected with 421

2024-03-16 Thread Stuart Henderson via mailop
On 2024/03/14 10:28, Julian Bradfield via mailop wrote:
> Their latest daftness (latest in my noticing it, anyway) is
> rate-limiting on the basis of too many recipients for a single
> message-id, where "too many" varies from 6 to 30. You'd think they'd
> never heard of organization mailing lists.

Same problem for the openbsd.org mailing lists:

"Gmail has detected this message exceeded its quota for sending messages
with the same Message-ID. To best protect our users, the message has
been temporarily rejected"

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Re: [mailop] Google unsolicited mail rejected with 421

2024-03-16 Thread Marco Moock via mailop
Am Thu, 14 Mar 2024 10:04:42 +0100
schrieb Marco Moock via mailop :

> Although, I send only a very small amount of mail to Google. Do they
> use that to calculate the rate?

I got that error again. I participated in some mailing lists with
gmail subscribers.
One of those subscribers has a forward to Google and I got an email
from their MTA that Google temp rejected it there too.

Does every attempt count here for Google's calculation?
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Re: [mailop] Google unsolicited mail rejected with 421

2024-03-14 Thread Andrew C Aitchison via mailop

On Thu, 14 Mar 2024, Johann Klasek via mailop wrote:


On Thu, Mar 14, 2024 at 12:03:46PM +0100, Marco Moock via mailop wrote:

Am 14.03.2024 schrieb Julian Bradfield via mailop :


On 2024-03-14, Marco Moock via mailop  wrote:

sendmail tried to deliver it 20 times during the night - this
morning I deleted the mail from mqueue.


That's a fairly aggressive retry strategy.


That is the default in sendmail.

Is there any standard that defines the retry rates or at least a best
practise?


The exim default is (description from the documentation):

*   *   F,2h,15m; G,16h,1h,1.5; F,4d,6h

This causes any temporarily failing address to be retried every 15
minutes for 2 hours, then at intervals starting at one hour and
increasing by a factor of 1.5 until 16 hours have passed, then every 6
hours up to 4 days. If an address is not delivered after 4 days of
temporary failure, it is bounced. The time is measured from first
failure, not from the time the message was received.



It depends on the average queue size and contention of the queue.
With many entry a queue runner interval might be exhausted easily and
retry streches over multiple intervals.
I would regard a 10 to 15 minute queue runner interval as acceptable.
If the queue is nearly empty the retry happens 4 to 6 times a hour.
That's not very aggressive meanwhile.


Exim's queue runner doesn't try to deliver every mail on every run through.
I hadn't expected that other queue runners would.


Our inbound queuerunner operates in permanent queue running mode which
could lead to a retry every minute if the queue is nearly empty.
This is more or less "aggressive" ...


An *inbound* queue runner sounds like a special case
- I would expect it to be more "aggressive".

--
Andrew C. Aitchison  Kendal, UK
   and...@aitchison.me.uk
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Re: [mailop] Google unsolicited mail rejected with 421

2024-03-14 Thread Johann Klasek via mailop
On Thu, Mar 14, 2024 at 12:17:39PM +0100, Slavko via mailop wrote:
> D??a 14. 3. o 12:03 Marco Moock via mailop napísal(a):
> 
> > Is there any standard that defines the retry rates or at least a best
> > practise?
> 
> RFC 5321, sect. 4.5.4.1:
> 
> In general, the retry interval SHOULD be at least 30 minutes...

A recommendation from the year 2008, one might re-consider this under
today's standards.

Beside this, MTA queue runners implement some dynamically calculated
backoff strategy based on time interval stretching (usually exponential)
or priority based, or a combination of these strategies.

Johann

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Re: [mailop] Google unsolicited mail rejected with 421

2024-03-14 Thread Johann Klasek via mailop
On Thu, Mar 14, 2024 at 12:03:46PM +0100, Marco Moock via mailop wrote:
> Am 14.03.2024 schrieb Julian Bradfield via mailop :
> 
> > On 2024-03-14, Marco Moock via mailop  wrote:
> > > sendmail tried to deliver it 20 times during the night - this
> > > morning I deleted the mail from mqueue.  
> > 
> > That's a fairly aggressive retry strategy.
> 
> That is the default in sendmail.
> 
> Is there any standard that defines the retry rates or at least a best
> practise?

It depends on the average queue size and contention of the queue.
With many entry a queue runner interval might be exhausted easily and
retry streches over multiple intervals.
I would regard a 10 to 15 minute queue runner interval as acceptable.
If the queue is nearly empty the retry happens 4 to 6 times a hour.
That's not very aggressive meanwhile.
Our inbound queuerunner operates in permanent queue running mode which
could lead to a retry every minute if the queue is nearly empty.
This is more or less "aggressive" ... 

Johann

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Re: [mailop] Google unsolicited mail rejected with 421

2024-03-14 Thread Slavko via mailop

Dňa 14. 3. o 12:03 Marco Moock via mailop napísal(a):


Is there any standard that defines the retry rates or at least a best
practise?


RFC 5321, sect. 4.5.4.1:

In general, the retry interval SHOULD be at least 30 minutes...

--
Slavko
https://www.slavino.sk/

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Re: [mailop] Google unsolicited mail rejected with 421

2024-03-14 Thread Marco Moock via mailop
Am 14.03.2024 schrieb Julian Bradfield via mailop :

> On 2024-03-14, Marco Moock via mailop  wrote:
> > sendmail tried to deliver it 20 times during the night - this
> > morning I deleted the mail from mqueue.  
> 
> That's a fairly aggressive retry strategy.

That is the default in sendmail.

Is there any standard that defines the retry rates or at least a best
practise?
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Re: [mailop] Google unsolicited mail rejected with 421

2024-03-14 Thread Julian Bradfield via mailop
On 2024-03-14, Marco Moock via mailop  wrote:
> sendmail tried to deliver it 20 times during the night - this morning
> I deleted the mail from mqueue.

That's a fairly aggressive retry strategy. If there's something about
that message gmail doesn't like, then retrying that often might be
enough to reinstate the limit each time.
Generally best to back off the retry rate after a couple of hours.
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Re: [mailop] Google unsolicited mail rejected with 421

2024-03-14 Thread Marco Moock via mailop
Am 14.03.2024 schrieb Julian Bradfield via mailop :

> They don't reject with 5xx because they're not rejecting that message,
> they are rate-limiting you or the network you're on.
> I get this often, because one user forwards their mail to
> gmail, including all the spam. Google rejects the spam, and from time
> to time also rate-limits me. Which I don't care about, because I send
> very little mail, and it goes through on the next run.

sendmail tried to deliver it 20 times during the night - this morning
I deleted the mail from mqueue.

Other mails to Google now go through, so it seems it is not a complete
limitation of my IP address/ISP.
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Re: [mailop] Google unsolicited mail rejected with 421

2024-03-14 Thread Julian Bradfield via mailop
On 2024-03-14, Marco Moock via mailop  wrote:
> Hello!
>
> Yesterday I replied somebody directly on debian-users (he uses a crappy
> mailer and sends to the author and the mailing list...).
>
> Gmail doesn't like this mail, but rejects it with a tempfail. I've now
> deleted it from mqueue.
>
> Mar 14 06:54:17 srv1.xyz sm-mta[498019]: 42DK6aqc496761:
> to=, delay=09:47:40, xdelay=00:00:03, mailer=esmtp,
> pri=5370980, relay=alt4.gmail-smtp-in.l.google.com., dsn=4.7.28,
> reply=421 4.7.28 Gmail has detected an unusual rate of unsolicited mail
> originating, stat=Deferred: 421-4.7.28 Gmail has detected an unusual
> rate of unsolicited mail originating
>
> It was only this message. Why don't they reject them with 5xx when they
> treat the mail as unsolicited?
> It was only this mail, my server wasn't abused by spammers.
>
> Although, I send only a very small amount of mail to Google. Do they
> use that to calculate the rate?

They don't reject with 5xx because they're not rejecting that message,
they are rate-limiting you or the network you're on.
I get this often, because one user forwards their mail to
gmail, including all the spam. Google rejects the spam, and from time
to time also rate-limits me. Which I don't care about, because I send
very little mail, and it goes through on the next run.

Google is brain-dead about "unsolicited" mail - whatever machine
learning it's doing, is crap.

Their latest daftness (latest in my noticing it, anyway) is
rate-limiting on the basis of too many recipients for a single
message-id, where "too many" varies from 6 to 30. You'd think they'd
never heard of organization mailing lists.

Julian.
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Re: [mailop] Google unsolicited mail rejected with 421

2024-03-14 Thread Marco Moock via mailop
Am 14.03.2024 schrieb Stefano Bagnara via mailop :

> On Thu, 14 Mar 2024 at 10:09, Marco Moock via mailop
>  wrote:
> > Mar 14 06:54:17 srv1.xyz sm-mta[498019]: 42DK6aqc496761:
> > to=, delay=09:47:40, xdelay=00:00:03, mailer=esmtp,
> > pri=5370980, relay=alt4.gmail-smtp-in.l.google.com., dsn=4.7.28,
> > reply=421 4.7.28 Gmail has detected an unusual rate of unsolicited
> > mail originating, stat=Deferred: 421-4.7.28 Gmail has detected an
> > unusual rate of unsolicited mail originating  
> 
> The full message from Gmail gives you more hints about the problem: it
> may be a rate limiting for the DKIM signing domain, for the SPF
> domain, for an URL included in the email, for the sender and so on.

IIRC it was the DKIM signing domain, but I can't see the full message
in the sendmail log.

> You need the full message to make a better guess, but, for example, if
> Google is receiving a lot of spam with a given URL domain in the body
> it may start rate limiting that content from every source, including
> you.

Is there a test address at google where I can send such messages to
test it?
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Re: [mailop] Google unsolicited mail rejected with 421

2024-03-14 Thread Stefano Bagnara via mailop
On Thu, 14 Mar 2024 at 10:09, Marco Moock via mailop  wrote:
> Mar 14 06:54:17 srv1.xyz sm-mta[498019]: 42DK6aqc496761:
> to=, delay=09:47:40, xdelay=00:00:03, mailer=esmtp,
> pri=5370980, relay=alt4.gmail-smtp-in.l.google.com., dsn=4.7.28,
> reply=421 4.7.28 Gmail has detected an unusual rate of unsolicited mail
> originating, stat=Deferred: 421-4.7.28 Gmail has detected an unusual
> rate of unsolicited mail originating

The full message from Gmail gives you more hints about the problem: it
may be a rate limiting for the DKIM signing domain, for the SPF
domain, for an URL included in the email, for the sender and so on.

E.g. the full message could be like this:
421-4.7.28 Gmail has detected an unusual rate of unsolicited mail originating
421-4.7.28 from your DKIM domain [#redacted#  36]. To protect
421-4.7.28 our users from spam, mail sent from your domain has been temporarily
421-4.7.28 rate limited. For more information, go to
421-4.7.28  https://support.google.com/mail/?p=UnsolicitedRateLimitError to
421 4.7.28 review our Bulk Email Senders Guidelines. #redacted# - gsmtp

The SPF tempfail error starts with the same words, too.
The URL one have a different prehamble.
I don't know how many other errors you can get, but if you want to
investigate you need the full error.

> It was only this message. Why don't they reject them with 5xx when they
> treat the mail as unsolicited?

They give you a tempfail because it is a rate limiting: so if you try
later it usually will work.

> It was only this mail, my server wasn't abused by spammers.
>
> Although, I send only a very small amount of mail to Google. Do they
> use that to calculate the rate?

You need the full message to make a better guess, but, for example, if
Google is receiving a lot of spam with a given URL domain in the body
it may start rate limiting that content from every source, including
you.

Stefano

-- 
Stefano Bagnara
Apache James/jDKIM/jSPF
VOXmail/Mosaico.io/VoidLabs
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[mailop] Google unsolicited mail rejected with 421

2024-03-14 Thread Marco Moock via mailop
Hello!

Yesterday I replied somebody directly on debian-users (he uses a crappy
mailer and sends to the author and the mailing list...).

Gmail doesn't like this mail, but rejects it with a tempfail. I've now
deleted it from mqueue.

Mar 14 06:54:17 srv1.xyz sm-mta[498019]: 42DK6aqc496761:
to=, delay=09:47:40, xdelay=00:00:03, mailer=esmtp,
pri=5370980, relay=alt4.gmail-smtp-in.l.google.com., dsn=4.7.28,
reply=421 4.7.28 Gmail has detected an unusual rate of unsolicited mail
originating, stat=Deferred: 421-4.7.28 Gmail has detected an unusual
rate of unsolicited mail originating

It was only this message. Why don't they reject them with 5xx when they
treat the mail as unsolicited?
It was only this mail, my server wasn't abused by spammers.

Although, I send only a very small amount of mail to Google. Do they
use that to calculate the rate?

-- 
kind regards
Marco
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