Open Mail Relay

[Mikhail]

On 14.08.2010 17:29, peter at vfemail.net wrote:
> I've reviewed my mail logs for the past couple of days and I can't
> find any entries for any mail addressed to the complainer's domain
> name except mail that should have been sent.

You can try it yourself, with telnet and proper smtp commands. For 
example, telnet from outside of your organization to your mail server 
and issue:

ehlo mydomain.com
mail from: foobar at example.com
rcpt to: foobar at example.org
data
test mail
.

You actually have to get error message about relay denied for you. If 
you don't - you're in trouble.
If you do recieve such message - you relay is closed and probably you 
have spam worms who send emails from legit user, or something like that.

Be well.