I am noticing very slow performance both when sending a message via SMTP and
also the amount of time it takes for that message to plop into the inbox.

When sending to our Courier .38 server with a mail client, the delay is between
15 and 20 seconds from the time you click "send" to the time the message is
finally sent. It is up to 30 seconds later that the message is finally
delivered in the inbox (clicking "receive" repeatedly). which is strange, since
it's the same machine for both SMTP and IMAP (or pop...same results)

The same behavior happens for a routed SMTP message (if it was sent by another
server to our server). Significant delay.

To complicate matters, we also run squirrelmail (webmail) on the same box, and
when a message is sent via SM's webmail interface, the message is sent in a
second, and appears instantly in the inbox! Just as I would expect!

So I don't know where to start looking. I disabled DNS lookups, disabled all
RBL type lookups, restarted courier, and nothing.

Anyone have any idea where I should start looking to troubleshoot this doozie?
The machine only has about 8mb free ram (an issue we will fix shortly), but sits
on a hardware SCSI raid

TIA,

(running on RedHat 7.1, hardware is dual 600mhz CPU HP NetServer)