> How can qmail *possibly* save enough bandwidth elsewhere to make up
> the additional 1.5MB of traffic it generates per digest?

Several ways. The biggest one for most sites is DNS lookups.

sendmail rewrites every address it sees. That includes header addresses
as well as envelope addresses. Unless you've massively hacked your
sendmail.cf, rewriting always means talking to DNS. sendmail also uses
DNS to handle host qualification.

qmail uses local syntactic rules for host qualification, and it doesn't
even look at headers in transit. (Except to count Received lines.)

If you give me a log of your DNS queries I'd be happy to show you which
ones qmail would have avoided. Please include outgoing as well as
incoming---otherwise we can't tell which answers were in cache.

There are savings in other areas too. Would you like to continue this
discussion on comp.mail.misc?

---Dan
Sick of sendmail? Don't get mad; get qmail. http://pobox.com/~djb/qmail.html