[Dovecot] LDA and postfix with recipient delimiter: documentation

[John Fawcett]

Just a comment about the documentation for postfix integration when
using receipient delimiter and delivery  of user+foo at domain.ext to 
user at domain:

http://wiki.dovecot.org/LDA/Postfix

I had some issues to get this working, so thought I'd share my
experience. Dovecot version 1.2.rc3. Postfix version
postfix-2.7-20090511.

I have no local (unix) mailboxes, everything is delivered to dovecot, 
so in postfix I have set mailbox_transport = dovecot. 
In this case the following syntax taken from the docs
does not work:

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

whereas the following does work:

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

I think that ${domain} is always what is wanted and only when 
${nexthop} happens to have the same value as ${domain} 
- for example when using a transport table entry like this:

/etc/postfix/transport
domain.ext	dovecot:

will the ${user}@${nexthop} form be deliverable. 
Can anyone see a reason for not using always ${user}@${domain} 
instead of ${user}@${nexthop}?


John