One of my servers seems to be rather slow to connect to many others on
the net (I've noticed this primarily in outbound email).  netstat
shows a large number (close to my remote concurrency limit) in
SYN_SENT state.  My logs show over half the connections eventually
failing on the generic "unable to establish an SMTP connection" (which
defers the message for later retry). 

I find the same thing when I make manual (telnet host 25) attempts at
connections, and when I do it on my other server for comparison I get
snappy responses (to the exact same end-point, so I'm keeping other
environmental things close to the same, only seconds between the
attempts). 

So the issue would seem NOT to be the MTA install/config on the two
systems (qmail, for those who care anyway), but *something* else about
them.  Both are running RedHat 7.2 with lots of updates.  They both
have dual IPs (one static, one local) on one NIC, they're plugged into
adjacent ports on the same hub eventually connected to the DSL line.
A prophylactic reboot made no difference (not very surprising, but now
I don't have to worry about it).

So what else should I be checking?  Oh, load average is 2.0 on a
system running 2 copies of seti-at-home, i.e. no load to mention
beyond that (dual-processor system).  No swapping going on (640MB of
memory on that one).
-- 
David Dyer-Bennet, dd-b at dd-b.net  /  http://www.dd-b.net/dd-b/
 John Dyer-Bennet 1915-2002 Memorial Site http://john.dyer-bennet.net
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