I ran into this a couple of days ago, and pass it along in case others
are in the same situation and haven't noticed (or figured it out). My
main SMTP machine at Apple is behind a firewall (actually, in a border
zone, with firewalls on both sides).
One problem I've had for a while, which coincided with an upgrade to
sendmail 8.8, was that incoming SMTP connections took forever to get
started. you'd try "telnet public.lists.apple.com 25" (for example),
and it'd just sit there for a while, and finally kick in. If I did it
via localhost, there were no delays.
Grr. Drove me crazy, but I could never track it down further than it
seems sendmail was off in some DNS code.
Well, this week my firewall admin called to ask why my server was
beating its head against the firewall. Seems I was flooding his logs
with attempts to connect to various sites via port 113, which the
firewall had plugged.
Port 113 is the IDENT port. It turns out that sendmail, starting about
version 8.6, started attempting to do validations through IDENT, and
this is turned on by default (IMHO, that's a mis-feature. It ought to
be off by default). sendmail will send out the IDENT request and wait
for a response.
This isn't too bad for most environments, because of IDENT isn't
running, the return comes back immediately. Ditto if it is running. But
if you're in a firewall environment, nothing comes back, and so
sendmail ends up freezing until it hits the timeout. and then continues
on.
aha -- my mystical magical DNS delays. This functionality change is
seriosuly buried in the sendmail docs,a nd not at all clear even when
you know what you're looking for. Did you know you were doing IDENT
calls in sendmail? I didn't.
Anyway, setting "Timeout.ident" to 0s in the sendmail.cf fixes it.
If you're in a firewall situation, or if you aren't interested in using
IDENT, you might check into this. There might be delays in your system
you didn't know about....
chuq
--
Chuq Von Rospach (Hockey fan? <http://www.plaidworks.com/hockey/>)
Apple Mail List Gnome (mailto:[EMAIL PROTECTED])
Plaidworks Consulting (mailto:[EMAIL PROTECTED])
<http://www.plaidworks.com/> + <http://www.lists.apple.com/>
