reject_unverified_recipient returns wrong code

admin 15 Apr 2026, 16:30

Postfix is returning 450 (temporary defer) for unknown recipients instead of 550 (permanent reject). Sender's server keeps retrying for days.

1 comment

Transcom 15 Apr 2026, 18:00

Set unverified_recipient_reject_code=550 in main.cf. Default is 450 which doesn't help us.