NOQUEUE: reject: RCPT from : 550 5.1.0 : Sender address rejected: User unknown

saahib

I have been trying to resolve this issue from a while and I guess I need help to resolve it.

I have domain which was hosted on mailcow and then moved to google workspace, now whenever someone tries to send mail from that domain which is moved google workspace to another domain hosted on this mailcow server, I get following error:

For convinience, lets call domain hosted on mailcow as
domain-mailcow.com
And domain which is hosted on now on google workspace which was earlier on mailcow as :
domain-gworkspace.com

NOQUEUE: reject: RCPT from mail-vk1-f178.google.com[209.85.221.178]: 550 5.1.0 <hello@domain-gworkspace.com>: Sender address rejected: User unknown in virtual mailbox table; from=<hello@domain-gworkspace.com> to=<testac@domain-mailcow.com> proto=ESMTP helo=<mail-vk1-f178.google.com>

The above message is from mailcow postfix logs.

I have deleted that domain already form mailcow by first removing all mail accounts associated with it and then removing domain.

I also restarted postfix docker, still same issue, then restarted whole mailcow server yet same issue.

I believe Mailcow does rebuild user/domain postfix map when a domain / user is added / removed. Currently I am out of ideas, where to look.

Note, mails to domain-mailcow.com are coming just fine if I send from other domains or servers.

saahib

Further, from postfix config, I found that mailcow uses mysql directly for domain and user list, then I checked DB directly and found that my deleted domain-gworkspace.com was still there.

Then I checked the mailcow again and found it there too. Not sure if it was my error or something else, after removing it from there (via UI), issue has been resolved.