There is a so called catch-all-account (all emails for a specific domain are sent into this account no matter where they were sent to). On another server there is fetchmail running and getting those mails ... and should forward those mails to another server then, let's say if you send an email to firstname.lastname@example.org
it's sent to that catch-all-account ...
Now the 2nd server should be doing a fetchmail and forward the mail for the domain beta.com to another server BUT should also send it to the user specified in the original message (alpha).
Anybody has a solution? Maybe with procmail or something alike?