[wplug] SMTP delay

[duncanhutty at comcast.net]

I'm using postfix, spamassassin is setup as a content filter transport in master.cf. spamassassin's local.conf has skip_rbl_checks = 1 so all those network connections are not an issue.
However, I don't think it's a spamassassin problem because the delay occurs before it's even handed off to spamassassin by postfix.
Duncan Hutty
-------------- Original message -------------- 

Can you explain how you set up spamassassin? If you set it up as a sendmail milter that will certainly cause a delay as it does various checks on each message, some of which are DNS related. The delay isn't a big issue normally, it doesn't reflect how many messages per minute the machine can handle except when factoring in memory and cpu utilization. It might feel like it can handle only 4 messages a minute but in reality it can handle hundreds.
Brandon Poyner 
Network Engineer II 
CCAC - College Office 
412-237-3086 
-----Original Message-----
From: duncanhutty at comcast.net [mailto:duncanhutty at comcast.net] 
Sent: Monday, August 23, 2004 6:27 PM
To: wplug at wplug.org
Subject: [wplug] SMTP delay


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.
Advice/comments?
Duncan Hutty
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