>> I don't think the practice of connection caching is particularly selfish when
>> compared to the cost of having the connection torn down and then
>> with some frequency, when it's generally much cheaper for both the sender and
>> the receiver to just leave it open.
> Exactly. Although it is necessarily up to the client to decide, the server
> benefits as long as the connection isn't cached for very long.
I can see this when two systems have prearranged dedicated channesl
for high load exchanges, but in general, I disagree that it is
"cheaper" and definitely not for the receiver. I don't see how that
can be justified. Average SMTP session times last year of 10-15
seconds are now up to 4-7 minutes this year Thats better?
Please reread my message. Nowhere did I say that clients should cache
connections up to the 5 minute timeout - in fact I said the exact opposite:
Caching a connection for anything even close to five minutes is almost
certainly counterproductive - SMTP connection establishment isn't *that*
difficult. But holding on to a connection for just a few seconds can be quite
beneficial for systems handling high volumes of mail.
I have no idea why your servers are seeing longer averages, but I can assure
you it isn't our client that's doing it. When there are no more messages we
only keep connections open for a few seconds and this is not configurable.