Peter J. Holzer wrote:
So really you would only ever see a cached connection stay open that
long if, for a connection cache of size N, it had to connect to some
small server, but the remaining (rather large) queue went only to a
specific N-1 other servers, and so the first one sat idle for that
long. Seems rather like a corner case.
Right. Especially since N is usually very small (default is 1 according
to the 8.12 docs, 2 for 8.13 on a Redhat box), it seems rather unlikely
that a connection would sit idle for an extended time during a queue
There is really very little that needs to be done. Ideally, SMTP
should have just a few notes about this. Starter text:
SMTP clients using Connection Caching methods SHOULD NOT wait more
than a few seconds to prevent grabbing too many resources from SMTP
servers. If the SMTP client has no cached messages to send, it
immediately end the session by issuing the QUIT command. It is
highly recommended for SMTP clients to queue up the messages before
connecting rather than connect and hold the connection sitting idle
waiting for new mail to send.
Really, that is all I think that is needed. Just make both the client
and server aware and leave it open ended. Where in the docs?