The domain alias example.com resides in Plesk Automation, but it's mail service is configured on external mail server. On attempt to send a message to the address like firstname.lastname@example.org the delivery fails. The following error message can be found in
Jan 1 09:00:00 mail01 postfix/smtpd: NOQUEUE: reject: RCPT from ppa-mn.isp.tld[203.0.113.2]: 550 5.1.1 <email@example.com>: Recipient address rejected: User unknown in virtual alias table;
The mail service existed previously on the subscription, but was unprovisioned later. After that some records of the domain alias
example.com still present in Postfix configuration and prevent from correct mail delivery.
Such behaviour has been considered as a software issue #PPA-3052 and will be fixed in future product updates.
As a workaround manually regenerate Postfix maps on the Postfix node:
Create a backup of the directory
# postmap -s /var/spool/postfix/plesk/virtual > /var/spool/postfix/plesk/virtual # cat /var/spool/postfix/plesk/virtual |grep -v example.com > /var/spool/postfix/plesk/virtual # postmap /var/spool/postfix/plesk/virtual
# postmap -s /var/spool/postfix/plesk/sdd_transport_maps > /var/spool/postfix/plesk/sdd_transport_maps # cat /var/spool/postfix/plesk/sdd_transport_maps |grep -v example.com > /var/spool/postfix/plesk/sdd_transport_maps # postmap /var/spool/postfix/plesk/sdd_transport_maps
Note: replace example.com with the actual domain alias name.