"smtp->mda->smtp proxy" and serialmail

Hey,

I have a situation wherein I need to accept SMTP connections as the primary
MX for a domain, then push the mail back out to the actual destination smtp
server after running it through procmail. Normally smtproutes would work
great for this purpose, but I need to put each piece of mail through
procmail first and I don't want to know anything about the domain's user
accounts...


My question is two-fold:

1) If I deliver to a catchall account, then .qmail to procmail which
delivers to the
    Maildir and then use maildirsmtp to shove the mail back out to the dest
server,
    how does maildirsmtp know the *actual envelope recipient*

2) [OT] Is serialmail suited for this purpose? Is there a cleaner way to
force all mail
    through procmail without serialmail?


"TIA"

--
Tim Wesemann