> What is a typical case?

These are numbers reported for a commercial server behind a fractional
T1. Slightly less than 0.02% of the total Internet traffic is accounted
to messages with multiple recipients at the same host. 0.14% of the
total Internet traffic is accounted to DNS lookups from the mail system.

With qmail everywhere, the 0.02% becomes a bit more than 0.04%, but the
0.14% drops below 0.06%. That's an overall savings of 0.06%. There's
also a tiny bit more savings in Received lines and SMTP responses.

(Side note: The relevant DNS server supported negative caching. qmail's
savings are much more impressive for servers that don't support negative
caching, since almost all of the extra DNS queries that sendmail does
are for nonexistent domains.)

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