[ILUG] Rewriting addresses in Postfix

[Tony Groves]

I'm up against a problem with Postfix in that I want to rewrite address 
headers in certain messages but I can't get it to do it the way I want.

An example would be a message sent to an address such as "1234567 at fax". 
I want to have the To header rewritten as "1234567<fax at domain.com>" (so 
that the fax number is preserved for the fax server to detect) and the 
message routed to "fax at domain.com". So, in main.cf I add the line:
   canonical_maps = /etc/postfix/canonical_maps
and in canonical_maps:
   /^(\d+)@fax$/ $1<fax at domain.com>
and reload Postfix. The result is that the message gets rerouted as 
intended, and a new X-Original-To header is added showing the original 
address, _but_ the To header ends up with just "fax at domain.com", losing 
the fax number.

Can any Postfix expert out there tell me how I can get this working, please?

Thanks a lot.

Tony.