Dockermailserver: Sender address rejected: not own...
# troubleshootinga
Alex
10/11/2025, 7:06 PMI'm having issues with dockermailserver and lldap:
I can log into the mail account, but whenever I try to send email or someone tries to send me an email it fails. When sending the error says Sender address rejected: not owned by user
When receiving the error is "550 5.1.1 : Recipient address rejected: User unknown in virtual mailbox table"
Docker Mailserver Logs:
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mailserver | 2025-10-11T20:45:35.057632+02:00 mx postfix/submissions/smtpd[1969]: Anonymous TLS connection established from abcdefg.abcdefg.host.net[123.123.123.123]: TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (prime256v1) server-signature ECDSA (prime256v1) server-digest SHA256
mailserver | 2025-10-11T20:45:35.689348+02:00 mx postfix/submissions/smtpd[1969]: NOQUEUE: reject: RCPT from p5ddba50c.dip0.t-ipconnect.de[123.123.123.123]: 553 5.7.1 <sender@example.com>: Sender address rejected: not owned by user sender@example.com; from=<sender@example.com> to=<recpient@gmail.com> proto=ESMTP helo=<[192.123.123.123]>
mailserver | 2025-10-11T20:45:35.709144+02:00 mx postfix/submissions/smtpd[1969]: lost connection after RCPT from abcdefg.abcdefg.host.net[123.123.123.123]Alex
10/11/2025, 9:55 PMIn case anyone finds this in the future: The issue was incorrect LDAP filters in docker mailserver in combination with a uid that didn't match the local part of the email address.
It tried to match against the uid, but should have matched against the full email address. I.e. %s in the LDAP filters instead of %u (there is a github issue and pull request regarding this, but it wasn't clear that this is the issue: https://github.com/lldap/lldap/issues/1305 and https://github.com/lldap/lldap/pull/1312)
If the mentioned pull request is merged, this will be fixed