SymptomsIf domain with same name as server's hostname exists in Parallels Plesk Panel, then message to postmaster@$HOSTNAME will generate mini mailloop.
Additional informationBy default in QMail aliases are working for hostname, e.g. 'firstname.lastname@example.org' on server with hostname 'plesk.ru'.
However, if domain 'plesk.ru' defined in /var/qmail/controls/rcpthosts, then aliases from /var/qmail/alias stop working and QMail tries to deliver to local mailbox of domain 'plesk.ru'.
Most of the time there are not mailbox with name 'postmaster' and error occurs:
Jan 19 13:57:36 plesk qmail: 1263905856.563663 delivery 829938: failure: This_address_no_longer_accepts_mail./
This error generates error report and sends it to postmaster@HOSTNAME which also fails to deliver and also generates error report to postmaster@HOSTNAME
Steps to reproduce1. Create domain with same name as hostname
2. Send mail from non-reachable mailname to postmaster@HOSTNAME
The following errors are shown in maillog (/usr/local/psa/var/log/maillog)
Jan 19 22:26:16 plesk qmail: 1263907576.027810 info msg 20570933: bytes 264 from <email@example.com> qp 20042 uid 0
Jan 19 22:26:16 plesk qmail: 1263907576.055692 starting delivery 1: msg 20570933 to local firstname.lastname@example.org
Jan 19 22:26:16 plesk qmail: 1263907576.080261 delivery 1: failure: This_address_no_longer_accepts_mail./
Jan 19 22:26:16 plesk qmail: 1263907576.147058 info msg 20570936: bytes 851 from <> qp 20046 uid 2522
Jan 19 22:26:16 plesk qmail: 1263907576.185717 starting delivery 2: msg 20570936 to local email@example.com
Jan 19 22:26:16 plesk qmail: 1263907576.199249 delivery 2: failure: This_address_no_longer_accepts_mail./
Jan 19 22:26:16 plesk qmail: 1263907576.253974 info msg 20570934: bytes 1339 from <#@> qp 20050 uid 2522
Jan 19 22:26:16 plesk qmail: 1263907576.281193 starting delivery 3: msg 20570934 to local firstname.lastname@example.org
Jan 19 22:26:16 plesk qmail: 1263907576.300402 delivery 3: failure: This_address_no_longer_accepts_mail./
and ends up with
Jan 19 22:26:16 plesk qmail: 1263907576.300577 triple bounce: discarding bounce/20570934
However, depending on environment these mail loops may become indefinite.
ResolutionThe issue has been fixed in Parallels Plesk Panel v9.3.0 MU1. Please apply the latest available updates via Control Panel -> Home -> Updater > 9.3.0 or via the shell as
# /usr/local/psa/admin/sbin/autoinstaller --select-release-current --install-component base
After fix is installed, messages addressed to postmaster@$HOSTNAME that cannot be delivered will not create mail loops. However, if you wish to receive messages addressed to postmaster, you might want to create mailbox or mail alias 'postmaster' on domain whose name matches server hostname.