Mail delivery from or to particular domain fails: do not list domain example.com in BOTH virtual_alias_domains and virtual_mailbox_domain

Yevgeniy Shimanskiy

Updated January 13, 2026 19:09

kb: bug Plesk for Linux

Applicable to:

Mail delivery from or to particular domain fails, the following bounce message is received:

Undelivered Mail Returned to Sender
(...)
<jdoe@example.com>: User unknown in virtual alias table
The following record is found in var/log/maillog:

postfix/trivial-rewrite[15060]: warning: do not list domain example.com in BOTH virtual_alias_domains and virtual_mailbox_domains

The domain example.com is present both in virtual_alias_domains and virtual_mailbox_domain:

# postmap -s hash:/var/spool/postfix/plesk/virtual |grep "^example.com"
example.com 1
# postmap -s hash:/var/spool/postfix/plesk/vmailbox | grep example.com
example.com/jdoe/Maildir/
Hostname might be changed automatically during Plesk installation
The domain is configured with capital letter in Domains > Example.com and server hostname is configured with capital letter in Tools & Settings > Server Settings

Software issue in Plesk with ID #PPPM-11246.

Until the issue is resolved, apply the following workaround:

Login to the server via SSH
Change the hostname under Tools & Settings > Server Settings from Example.com to example.com and click OK