I have noticed that one of the most consistently rejected emails when
forwarded to Gmail, is an email from Google. I just rotate outbound IPs
on that message using ZoneMTA and it'll get through. Waiting for an IP
to clear a rate limit with Gmail just seems like bad business at this
point.
On 2022-11-24 10:20, Martin Flygenring via mailop wrote:
Hello all
For the past few weeks, we've noticed increasing queues on our
MX-servers when forwarding some emails to our users alternate
addresses, if that forwarding address is a gmail.com address. Most of
the mails go through without issues, but some end up getting deferred
with the error message:
421 4.7.28 [185.164.14.118 15] Our system has detected an unusual
rate of unsolicited mail originating from your IP address. To protect
our users from spam, mail sent from your IP address has been
temporarily rate limited. Please visit
https://support.google.com/mail/?p=UnsolicitedRateLimitError to review
our Bulk Email Senders Guidelines.
bj3-20020a170902850300b001895e356f00si917651plb.152 - gsmtp (in reply
to EOD command)
Now, the interesting part is that for almost 98% of the mails currently
in queue, Google is the original sender of the email.
Total mails deferred/in queue due to the above message, at the time of
writing: 2696
Top 3 original sender:
2582 gmail.com
38 google.com
22 calendar-server.bounces.google.com
For reference, we currently have 2.8m registered domains, meaning we
send millions of mails towards gmail on a monthly basis.
So while it is a very small amount of mails that end up in this state,
we are still puzzled about why. Especially when so many of the original
senders are gmail-addresses or other Google addresses.
I have been looking through our queues, and most often it looks like
very legit mails that gmail just doesn't want to accept. For example:
- Friends talking about a christmas lunch/dinner
- Someone who's heating at home isn't working
- Some friends talking about a LEGO build they're doing together
- Building management meetings
- Someone that's sad they can't join a presentation because they're on
vacation
.. and so on. Very innocent stuff.
We use SRS when forwarding, and every forward that users set up
requires verification by the forward recipient, by them clicking a link
to confirm they want to accept these forwards.
Looking at our graphs, between Oct 25th and Nov 7th we had 16 mails get
deferred/bounce because of the above error message. Since Nov 8th,
we're looking at somewhere between 250 and 1000 mails pr. day.
Sometimes the mail eventually goes through with delay, but there are
some that never make it through.
Is anyone else seeing similar issues when forwarding mails from
gmail.com, back to other addresses at gmail.com?
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