I want a setup where an e-mailaddress like [email protected] redirects mail to the folder foo. I've already got dovecot configured and tested. It is called by postfix with this line in master.cf:

dovecot unix    -       n       n       -       -      pipe
  flags=DRhu user=vmail:vmail argv=/usr/lib/dovecot/deliver -f ${sender} -d ${user}@${nexthop} -n -m ${extension}

I expect ${extension} to expand to 'foo' but it is always empty.

I've added

recipient_delimiter = +

to my main.cf.

How can I get it to work?

Update: I've got a catch-all alias that redirects @domain.com to [email protected]. It seems that the extension is empty because of this. So the question becomes: Can I have a catch-all so that [email protected] redirects to [email protected] without explicitly defining either the random or the ext part?