smtp relay abuse

From: Rob (anonymous_at_discussions.microsoft.com)
Date: 06/15/04 

Date: Tue, 15 Jun 2004 05:20:42 -0700

Running Win 2003 Server as a standalone with POP3
mailboxes, I am getting spammers relaying thru the smtp
virtual server, even though I have restricted Relay
Access by selecting the radio button "Only the List
Below", with no computers listed, and have checked the
box "Allow all computers that successfully authenticate
to relay". Authentication Access has "Anonymous Access"
and "Integrated Windows Authentication" checked. (I tried
unchecking Anonymous Access but that does not stop the
unauthorized relay.) It almost seems to me that the
spammers are somehow authenticating on this server. Any
ideas as to how the spammers are accomplishing the relay
and what can be done to stop it. So far, my only remedy
has been to stop the smtp virtual server, which of course
renders my email system inoperable.

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