On Tue, 11 Nov 1997, John Henders wrote:
> I remember seeing something like this a few years ago with smail when it
> was set to a shorter timeout. It used to be a "feature" of sendmail that
> it would hold open an smtp connection after delivering mail to a site,
> just in case there was more mail to be sent later (or that's the
> rationale I heard for it) I haven't seen this in quite a long time so
> I'm guessing that that feature was disabled by default or removed. Maybe
> Netscape adopted that feature for their own mailer, (assuming they use
> their own mailer) or are running an older version of sendmail.
It is called connection caching. The connections aren't supposed to be
cached too long, but sometimes admins mess up and increase timeouts a
little too long. In fact there are strong warnings about misconfiguring
connection caching in the SMOG. This functionality is being improved in
Sendmail, mainly because it offers a lot of promise.
Zmailer also makes heavy use of connection caching. It holds
connections open up to certain limits, in case more mail is destined for
that site. These connections are managed by a resident daemon
(scheduler). Zmailer will guarrentee that all mail destined for that
site, goes out that connection. This means that Zmailer can direct
messages from multiple sources but to a single destination, all down a
single connection. Unfortunately, Zmailer is affected with
version-of-the-month syndrome.
The Netscape mail server is a derrivitive of post.office (from
www.software.com). I don't think anyone knows how this stuff works under
the hood, and it probably changes in every version.
Tom
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