>Есть связка Postfix + MySQL + Courier-imap + Postfixadmin
>в базе есть пользователь test@domain.com Отправленные ему письма исправно ложатся в майлдир. Но если отправить письмо скажем на postmaster@@domain.com (у которого алис на системного пользователя systemuser@domain.com), то оно возвращается с ошибкой 550 <systemuser@domain.com>: User unknown in virtual mailbox table;
>
>В MySQL пользователь systemuser@domain.com прописан. алисас postmaster тоже.
>
>Что делать?
smtpd_reject_unlisted_recipient (default: yes)
Request that the Postfix SMTP server rejects mail for unknown recipient addresses, even when no explicit reject_unlisted_recipient access restriction is specified. This prevents the Postfix queue from filling up with undeliverable MAILER-DAEMON messages.
The recipient domain matches $mydestination, $inet_interfaces or $proxy_interfaces, but the recipient is not listed in $local_recipient_maps, and $local_recipient_maps is not null.
The recipient domain matches $virtual_alias_domains but the recipient is not listed in $virtual_alias_maps.
The recipient domain matches $virtual_mailbox_domains but the recipient is not listed in $virtual_mailbox_maps, and $virtual_mailbox_maps is not null.
The recipient domain matches $relay_domains but the recipient is not listed in $relay_recipient_maps, and $relay_recipient_maps is not null.
This feature is available in Postfix 2.1 and later.
Проверяй есть ли запись о systemuser@domain.com в $virtual_mailbox_maps.