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This is a non-trivial problem. I've spent nearly 3 hours in chat with Google Support. This escalated to 2nd level and then internal support. It may be related to SMTP servers bouncing messages.

I am not actually expecting a resolution from this message. What I hope is some SMTP admins can make suggestions on how to get more information to resolve this issue. Something with which I can prod Google Internal Support team.

We have a Google Workspace for Business and are using multiple Groups.

Summary of issue for our Members group:

  1. Msg received from certain users, like myself.
  2. Msg is posted to group website conversation.
  3. Msg is 'bounced' per Email Log in Workspace.

Quirks of issue:

  1. Msgs from most users are processed through to members of Group.
  2. Msgs from users that bounce in Members do not bounce in other groups.
  3. All groups are configured the same.
  4. Msg content, not the user, may be the problem but I can't identify common aspects. Especially across multiple domain SMTP servers as mentioned in next item.
  5. Google suggests it is the domain SMTP server for recipient user's email that is bouncing the message. That may be correct but emails are being bounced by servers for gmail.com, att.net, comcast.net and a few others. That seems strange. No suggestion on why these diverse servers would all reject the emails.

The log entry appears as:

Aug 19, 2022, 3:27:54 PM  Forwarded from group: members@domain.org
Aug 19, 2022, 3:27:54 PM  Accepted from group forwarding
Aug 19, 2022, 3:27:54 PM  Bounced   Message rejected. See https://support.google.com/mail/answer/69585 for more information.

For a non-bounce the 3rd line says 'Delivered'. My understanding (guess?) of the sequence is:

'msg' >> [smtp servers] >> [group server] >> 
    [google smtp] >> [users smtp] >> user
                   ^ {bounce}

My suspicion is there is another Google server involved that is doing the bounce and not the [users smtp] server.

I have dumped the email log to a spreadsheet which shows more details on the processing sequence. It doesn't provide any usable info as far as I can tell.

Any suggestions on resolving this?

Update: Is there an SMTP server online where I can see the logs? I could create a users in the Group for that server. If a message bounces logs on the SMTP server should show why.

Update 2022/8/24: As stated in comment sent msg from group web interface to Mail Genius. It didn't bounce. A msg sent from my personal account showed Google mail servers spam blacklisted. Forwarding results to Google support.

rm1948
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  • Rejections at SMTP stage are not just binary results, they come with a status code, plus almost always an extended status code and a textual explanation. Get a few such sample status messages, I expect they are all alike and all point to which of the common issues you have. – anx Aug 20 '22 at 02:15
  • @anx - Google tech support stated that groups only get the generic "bounced" response when I pushed for more details. If I knew why they were bouncing I could address the issue. Suggestions from them were signatures and links in messages. My underlying question is why do all the different servers generate a bounce? Wouldn't some bounce but others pass on the messages? IMO that indicates it is a Google server doing the bounce. Thanks for you response. – rm1948 Aug 22 '22 at 21:50
  • The help article linked in the log you quoted claims "Gmail returns a message reflecting the response provided by the recipient’s server." - what exactly does that *"message reflecting the response provided"* look like? – anx Aug 23 '22 at 11:38
  • Send one such failing message to an address provided by a service like https://www.mail-tester.com/ and share the link. (if delivery fails for some group members, but not others, use that as a manually added group member for better diagnostics.. otherwise just add that as an extra recipient in the CC field on top of the group address so we have at least something to look at). – anx Aug 23 '22 at 11:44
  • anx - "Message rejected. See https://support.google.com/mail/answer/69585 for more information." That's it. The link to support is useless. This is one of the big frustration. Not enough information to know why it bounced. – rm1948 Aug 24 '22 at 17:47
  • I sent a message from the group web interface with MailGenius. It did not bounce. Results are at https://app.mailgenius.com/spam-test/4e27d1 I sent an email from my GMail account to Mail Test: https://www.mail-tester.com/test-iyuhbqayu Google's servers are blacklisted: 209.85.128.190 mail-yw1-f190.google.com. and 209.85.160.47 mail-oa1-f47.google.com. Would the SMTP servers getting the outgoing message check my email for problems? Again, some messages being bounced are not from GMail. If that is why messages are bounced there isn't much I can do about it. – rm1948 Aug 24 '22 at 19:09
  • That sounds like some anti-spam-measure, like SPF or DKIM, gets in the way .. and some recipient's servers may be more strict than others. The forwarding server (= yours) needs to rewrite some headers to not violate those measures, and sometimes there are bugs that lead to incorrect handling and hence bounced forwards. There may be not much you can do except contact support, or not forward externally at all. Maybe the recipients can use a mailbox hosted at your provider? – Hannes Erven Aug 25 '22 at 23:59

1 Answers1

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@anx suggested using mailing list message checking site mail-tester.com. I tried it and then MailGenius. This lead to resolution of the problem.

A URL that Google's standard footer injects into the message is a link to the message in the group's web interface. In our case the URL is 163 characters. Messages with URLs longer than 120 characters are typically rejected as 'spam' candidates.

Disabling that footer allows our messages to pass.

Google tech support suggested the bounces were due to a URL but never hinted it could be their injected URL. Obviously I didn't consider it since it is a standard item. Silly me.

I've been monitoring the email log. There are no bounces for new messages. There are bounces when someone replies to an older message that has the URL. Members are cautioned about replying to older messages.

Thanks for the assist, @anx.

rm1948
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