IMail has an SMTPD32 process ("SMTP Daemon") that receives incoming E-mail, and stores it in the spool. There will only be 1 instance of SMTPD32.exe running at any time. It can process hundreds (thousands?) of simultaneous incoming E-mails.
in practice, IMail SMTPD can't handle that many. It's very easy and repeatable to cause any Imail box, that is otherwise working fine, to go deaf (refuse any more SMTP connections) when hit with a big does of mail from IMGate. And I'm not talking about 100's of simultaneous SMTP sessions, but maybe 10 or 20. IMGate defers the msgs and succeeds later.
Anybody want me to do it to them? :))
The limitaton on IMail SMTPD is obviously its ability to queue the msgs to disk, which is a disk bandwidth issue. There may be other limitations within in Imail or the Windows tcp/ip stack, but the disk bandwidth will limit first and not be amenable to tweaking.
The disk bandwidth also comes into play when delivering queue-to-mailbox, and POP/IMAIL/webmail mailbox reading.
So the rule is always prioritize your mail server budget for disk bandwidth. (same rule applies to IMGate)
Len
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