We've had that rule for probably 10y or so at this point, as to why, blame SMTP for rcpt and data being separate. GSuite domains can define rules on what they will/won't accept, and in order to deny such messages in the smtp transaction and not create backscatter by bouncing them later, we have to restrict the transaction to users in the same domain.
And the setting isn't in mailman, it's in your MTA, most of them have a setting to split by domain and not mx. Searching turned up instructions for sendmail and exim, but I failed to find the postfix one, I know you can set postfix to have max recipients of 1, but that seems like overkill. You can also tune how quickly you retry on partial failure on some servers, there's no reason to wait as long (or maybe at all) when some succeed and others get a 4xx error (though, honestly it depends on which 4xx error, but even if the others are all longer term problems, that'll just be one quick retry to figure that out) Brandon Brandon On Wed, Sep 25, 2019, 2:22 AM Simon Lyall via mailop <mailop@mailop.org> wrote: > > Just had a bunch of people at a domain get unsubscribed from this list. > Appears to be some weird Google rule (which probably made sense with they > were not the MX for 30% of all active domains) > > Any chance of them fixing it (or failing that a quick work-around for > mailman)? . It looks like people have been complaining about it for a few > years though. > > us...@example.com > SMTP error from remote mail server after RCPT TO:<us...@example.com>: > host alt3.aspmx.l.google.com [108.177.97.26]: > 451-4.3.0 Multiple destination domains per transaction is unsupported. > Please > 451 4.3.0 try again. w4si7917585pjr.54 - gsmtp: > retry timeout exceeded > us...@example.com > SMTP error from remote mail server after RCPT TO:<us...@example.com>: > host alt3.aspmx.l.google.com [108.177.97.26]: > 451-4.3.0 Multiple destination domains per transaction is unsupported. > Please > 451 4.3.0 try again. w4si7917585pjr.54 - gsmtp: > retry timeout exceeded > > > -- > Simon Lyall | Very Busy | Web: http://www.simonlyall.com/ > "To stay awake all night adds a day to your life" - Stilgar > > > > _______________________________________________ > mailop mailing list > mailop@mailop.org > https://chilli.nosignal.org/cgi-bin/mailman/listinfo/mailop >
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