a few weeks back, i posted the following procmail rule that works along
with sendmail 8.8 configs to capture the envelope address into email.
EXTRA=$1
:0 fhw
* EXTRA ?? @
| formail -I "X-Envelope-To: $EXTRA"
to go along with that, here is the fetchmail configuration to suck up
the email and redistribute it locally. this should go into
~root/.fetchmailrc and then run fetchmail -s from cron on some schedule
to your liking.
poll server <server> user <user> password <password> to * here
with the <> fields replaced as appropriate. fetchmail automatically
scans for the X-Envelope-To field and uses that for local delivery.
any email that doesn't have that, or has a bogus address will go to
root.