Date: 6 Mar 1996 16:39:01 GMT
Message-ID: <19960306163901.14313.qmail@koobera.math.uic.edu>
From: djb@koobera.math.uic.edu (D. J. Bernstein)
To: drums@cs.utk.edu
Subject: Re: re PIPELINING

> My experience contradicts this.

Really? What percentage benefit could your host possibly get from
multiple RCPTs? For outgoing messages this is very easy to measure:
for each message, count the number of recipients and the number of
hosts; scale by message size if you want; add up the results for all
messages.

Note that the situation is different for non-Internet-connected hosts.
For example, hosts behind a firewall typically have to send all messages
through a gateway. They should use a protocol designed for that---like
the BITNET protocol. :-)

> We run a mailing list with 5000 recipients.
  [ best performance: 20 domains per envelope; 2-hour delivery overall ]

qmail sustains performance of <1 second per SMTP connection with its
default concurrency limit of 20; that's already <2 hours for your
5000 recipients. If most of your recipients are in the U.S. you'll do
even better. You can, of course, use a much higher concurrency limit.

---Dan