I have a Google Workspace email account and mailcow running on a compute VM. I have setup Google relay server for outgoing emails from Mailcow and on Google Workspace I have set up split-delivery to receive
Google workspace: user1@domain.com
mailcow: user2@domain.com
external: user3@gmail.com
- Emails from mailcow account to other mailcow accounts-> no issues
- Emails from mailcow account to external email accounts and vice versa -> no issues
- Emails from Google workspace account to mailcow account -> no issues
- Emails from external email accounts to Google workspace account and vice versa -> no issues
Failure
- Emails from mailcow account to a Google workspace account, where both have the same domain
In the logs, I see mailcow not using the relay and just doing a MX lookup and trying to connect on port 25 which is blocked on all Google compute VMs and so it times out.
4AA37100E28: to=user1@domain.com, relay=none, delay=1937, delays=1787/0.01/150/0, dsn=4.4.1, status=deferred (connect to alt4.aspmx.l.google.com[172.217.197.26]:25: Connection timed out)
Here is an example log of sending an email to an external email address where the SMTP relay is used correctly and the mail is sent:
DBC78100DC1: to=user3@gmail.com, relay=smtp-relay.gmail.com[74.125.124.28]:587, delay=0.73, delays=0.5/0.05/0.06/0.12, dsn=2.0.0, status=sent (250 2.0.0 OK 1706830772 bm12-20020a056e02330c00b0036396107e28sm36967ilb.3 - gsmtp)
How can I fix the above issue and make sure every single email, whether its within the domain or to external gets sent through the SMTP relay?
Thank you
Shri