Php – Filter email in POSTFIX with PHP

This is called a "catch all"

Mapping is done using /etc/postfix/virtual file.

vi /etc/postfix/virtual

Append code as follows, replacing domain and emailusername with actual values:

@yourdomain.com emailusername

Save and close the file. Run following command:

postmap /etc/postfix/virtual

Also make sure you have following line in /etc/postfix/main.cf file:

virtual_alias_maps = hash:/etc/postfix/virtual

If you just added above, line reload postfix:

service postfix reload

From http://www.cyberciti.biz/faq/howto-setup-postfix-catch-all-email-accounts/

Why not use sender_bcc_maps and recipient_bcc_maps to copy mail to a dedicated archive domain - say, archive.foo.bar - delivered via transport(5) to an MDA that stores archived mail in dedicated mailboxes?

No second instance needed, and clean solution all-round.

You can use a regex or PCRE map type to map al senders or recipients to mailboxes in the archive domain, e.g.:

/etc/postfix/sender-archive-pcre: /^(.*)@foo\.bar$/ $1-outbound@archive.foo.bar

/etc/postfix/recipient-archive-pcre: /^(.*)@foo\.bar$/ $1-inbound@archive.foo.bar

And in transport(5): @archive.foo.bar unix:your-archive-mda

As for which delivery agent to use: I very strongly suggest you use dovecot 2.x, either the deliver mda or the LMTP server; both have full sieve filter support with the pigeonhole plugin.