dovecot - Jun 2007 - (OT) Advice on best way to collect mail from multiple domains and deliver to users via Dovecot IMAP.

Hi

Sorry if this is an inappropriate question to ask here. If it is maybe there
is a better place to ask this question?

I would like to collect email sent to multiple users (with previously
unknown usernames) sent to multiple domains and then deliver this email to a
specific set of users on my server based upon some predefined rules, with a
catchall for mails that aren't caught by these rules.


So as an example, I might have domains:- example.com, example.co.uk,
someotherdomain.com and I'd like to say to a sender "just send a mail
to
anything at example.com". I'd like to be able to make up recipients on
the fly
when subscribing to a service so that I can filter mails to this address out
at a later time.

The method I devised when I set this up using dovecot .99 is as follows.

I currently have the hosting service for the domains forwarding all email to
a singular mailbox at my ISP and I user fetchmail to pop3 the mail down from
this one mailbox. 
The mail is then passed to postfix where I use the luser_relay option to map
all unknown recipients to a local address so that it doesn't get bounced.

Postfix then delivers the mail via the mailbox_command to maildrop where a
series of rules inspect the envelope headers and write the mail using the
"to" option to an appropriate maildir for the target user.

Is this a good approach?
Would I be better off using dovecot LDA and sieve?

Any advice or ideas would be gratefully received.

Daveh