Hi All, I have very serious problem with my mail server. I have SMTP server on IIS with Invalid IP and is published behind ISA server using Mail wizard as secure NAT client. I find lots of spam mails going out from this mail server using external IP address of ISA server. I have enabled SMTP filter on ISA, but i doubt its working or not? I find following messages in my Event viewer of ISA server. THE SMTP command exceeded its length. In details it shows as mail from some xyz@xxxxxxxxxx Please advice as my Event viewer is full of such messages. Is it any kind of Mail attack? What has to be done to stop such activity. Please help me out, Regards, Vinay.