I've got similar problem with mails with ISPConfig and Debian 4.0
Feb 3 14:58:57 stock postfix/pipe: C1879109E58: to=, relay=maildrop, delay=0.09, delays=0.06/0.02/0/0.01, dsn=5.1.1, status=bounced (user unknown. Command output: Invalid user specified. )
Full mail log located here
When I tried to change postfix config for listed above then error occured:
Feb 3 15:38:05 stock postfix/cleanup: 3E9B210A4F4: message-id=<email@example.com>
Feb 3 15:38:05 stock postfix/qmgr: 3E9B210A4F4: from=, size=2106, nrcpt=1 (queue active)
Feb 3 15:38:05 stock postfix/pipe: warning: file /etc/postfix/master.cf: service maildrop: unknown macro name: "domain"
Feb 3 15:38:05 stock postfix/smtpd: disconnect from localhost.localdomain[127.0.0.1]
What is strange, that "to=" parameter isn't specified (log is unedited).
maildrop -d my_email@my_domain.com
shows "Invalid user specified"
while I'm sure there is such user within mysql DB of IspConfig
Does the maildrop use some cache or something or should it use straight from mysql? Because I don't see any queries to DB.