Anti spam on Exchange Server

Kyran,

The following measures have been implemented on our Exchange Server and do the job quite nicely:

In the properties page for the Internet Mail Service, select the Routing tab.

You have two options, the first is to select Do not reroute incoming SMTP mail. If you select this all attempted Spammers will get a message saying 'Relaying is not allowed'. However this will generate a Non-Delivery Report (NDR) which can be used to create a flood of Non-Delivery Reports against another mail server, known as Reverse Unsolicited Commercial E-mail (RUCE).

A better option is to set Reroute incoming SMTP mail and supply the name(s) of your valid Domains with the Should be accepted as "inbound" option.

Then to prevent Spammers openthe Routing Restrictions page and enable Hosts and clients with these IP addresses, but do not enter any IP Adresses. This has the effect of making the MTA check whether a message is for a local valid recipient. If it is not the relay is terminated but a NDR is not generated so you are protected against UCE and RUCE.

Hope this helps.

Check the following article for more detail:

http://www.microsoft.com/technet/exchange/relay.asp

Regards,

JB.