[wplug] SMTP delay

[Bill Moran]

duncanhutty at comcast.net wrote:

> I am testing a mail server and have been told that even an old k6II 500
> with 320MB should be able to cope with so many zillion messages a month
> with no problem even with LDAP and spamassassin.
> When I (handwavingly) test this setup, sending a single, tiny message,
> it takes about 15 seconds to 'finish' transmitting the message to the
> mail server (on the LAN). I am calculating that time from monitoring
> Outlook's send and receive dialogue box.
> When I test from the same machine to my ISP's mail server (obviously
> NOT on the LAN), the same message takes <1s to transmit.
> Trying to eliminate error and check my testing, I made sure that there
> was no other traffic/activity on the server. I monitored
> /var/log/mail.log and saw 16s between the client connecting and
> disconnecting.
> Seems to me like 16s is a long time for a 1k message even on a vintage
> PC like this. Are my expectations out of whack?
> Or should I be expecting better performance and investigating why this
> is so slow?
> If I move the LDAP server to another machine, would I expect better
> perfomance? I would think that network vs. localhost lookups would be
> slower, but maybe removing the cpu cost to another cpu might help.

The potentialtech.com mailserver is only an 800mhz and it's also our
HTTP and DNS server.  I see no such delays on it, so I can't imagine
that it would take a 500mhz 15 seconds to transmit 1 email.

It sounds suspiciously like a timeout.  Are you sure the DNS is working
as the mailserver would expect?  I've seen more network problems boil
down to a program trying to do a reverse DNS lookup and timing out.
What MTA are you using?  Can you increase logging to determine exactly
where the 15 seconds is occurring?  I mean, is it between the HELO and
the DATA?  Or is it after the last line of the DATA has been transmitted?
This might give a clue as to what the holdup is.

I can't imagine any legitimate reason why that machine would take so long.

-- 
Bill Moran
Potential Technologies
http://www.potentialtech.com