Postfix + maildrop + recipient_delimiter

I suddenly noticed issues with Postfix not accepting e-mails that are tagged (“user+TAG@fqdn”) anymore. Even though it always had.

Postfix main.cfg:

recipient_delimiter = +

Log snippet:

Apr 16 13:07:52 vm-dns-mail postfix/pipe[6119]: 55D1C2005E4: to=<[email protected]>, 
relay=maildrop, delay=0.06, delays=0.01/0/0/0.05, dsn=5.1.1, status=bounced 
(user unknown. Command output: Invalid user specified. )

Tried to find what’s wrong in MySQL, change the delimiter, Debug Maildrop, etc. Not much progress… 🙁 And after 6 hours I was starting to get annoyed.

The clue was changing this line in master.cfg:

maildrop unix - n n - - pipe
 flags=DRhu user=vmail argv=/usr/bin/maildrop -d ${recipient}

to

maildrop unix - n n - - pipe
 flags=ODRhu user=vmail argv=/usr/bin/maildrop -w 90 -d ${user}@${nexthop}
 ${extension} ${recipient} ${user} ${nexthop}

Source where I ripped the line from.