Procmail with Postfix and virtual mailboxes

Question

I have setup a working SMTP, IMAP and POP3 server using Postfix and Dovecot. I have setup virtual mailboxes using the format /home/vmail/%d/%u, where %d is the domain (e.g. camilstaps.nl) and %u is the 'user' (e.g. info) - thus [email protected] has /home/vmail/camilstaps.nl/info. I now would like to setup Procmail to use filters.

I have read this wiki, for example, but I don't think it applies to my situation with virtual mailboxes. I have not enough knowledge of Procmail to do this all by myself.

Could anyone explain to me or give me a link where to start? I searched on google but only came across useless forum threads, no documentation or tutorial. That makes me wonder if it's even possible to do this.

Answer 1

WARNING: It should work but I have not tested it myself.
RECOMMENDED IMPROVEMENT: I would advice making both postfix and dovecot use mysql (or another database) to store valid virtual user.

Discussion about procmail script in /etc/procmailrcs/

/etc/postfix/main.cf:

# list of valid/served virtual domains
virtual_mailbox_domains = example.com example.net
# verification of virtual recipient validity
virtual_mailbox_maps = hash:/etc/postfix/virtual
# transport for deliveries to virtual mailboxes
virtual_transport = virtualprocmail:dummy

virtualprocmail_destination_recipient_limit = 1

/etc/postfix/virtual (requires compilation with postmap):

[email protected] Jane Doe
[email protected] John Doe

/etc/postfix/master.cf (replace virtualuser with real OS account name owning the virtual mailboxes):

virtualprocmail unix - n n - - pipe flags=DRXhuq user=virtualuser 
  argv=/usr/bin/procmail -m E_SENDER=$sender E_RECIPIENT=$recipient ER_USER=$user ER_DOMAIN=$domain ER_DETAIL=$extension NEXTHOP=$nexthop /etc/procmail.d/default.rc

/etc/procmail.d/default.rc (must be readable by virtualuser):

# You should add some sanity chces of ${ER_DOMAIN} and ${ER_USER}

# Add trailing / if you want to use maildir directory instead of mailbox file
DEFAULT=/home/vmail/${ER_DOMAIN}/${ER_USER}