[Mimedefang] Sendmail::Milter

[Joseph Brennan]

One connection per 5 minutes is extremely low.

There are mailing list products that send to 1 recipient per message
and close the connection after each one.  They don't pipeline when
running a queue either.  I think the products run their own queue
instead of handing it off to a sane MTA.

I don't know the product names but we've been on the receiving end of
them.  We've currently got default ClientRate: 20 and ClientConn: 10
as a compromise (20 per second, 10 at a time).  This is on systems
fielding about 200,000 messages a day.

Constant Contact regularly hits even that ClientRate limit.  A few spam
sources hit it each day too.

Joseph Brennan
Columbia University Information Technology