🚀 go-pugleaf

Another way to do the domain based headers/envelope is to 
have it done in the mailer specific rewriting rules of sendmail.
Sendmail 5.61 with IDA enhancements even has specific rewriting rules
for sender and recipient and for the header and the envelope,
that is in toto 4 separate rewriting rules available.

We use this at the Danish Internet/UUCP backbone to customise
our uucp connections, of which we have a little over 100.
Each of these have a mailer specification, which tells
if they need the header in domain-style, the envelope in
bang style etc. We have even added support for 8-bit mail
in this way on a site dependent basis, handeling different kinds of
7- and 8-bit character sets and conversion between them.

Keld Simonsen, DKnet
keld@dkuug.dk