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I have a new exchange 2003 server. I use a 3rd party spam filtering company. My dns is setup so email goes to the spam filtering company first, they filter the email for spam and viruses, and then shoot me only the good stuff. The problem I am having is that spammers are circumventing dns by blasting my server directly (ignoring dns) with smtp messages. Unfortunately my firewal doesn't seem to have any advanced options to allow me to configure to block smtp traffic unless from the ip range of my spam filtering company. I believe their is an option in exchange to allow one to specify an ip range that the server will allow incoming smtp from. I would then like to reject emails coming from all other ip addresses. My router is a 2wire AT&amp;T dsl basic router.
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I have a new exchange 2003 server. I use a 3rd party spam filtering company. My dns is setup so email goes to the spam filtering company first, they filter the email for spam and viruses, and then shoot me only the good stuff. The problem I am having is that spammers are circumventing dns by blasting my server directly (ignoring dns) with smtp messages. Unfortunately my firewal doesn't seem to have any advanced options to allow me to configure to block smtp traffic unless from the ip range of my spam filtering company. I believe their is an option in exchange to allow one to specify an ip range that the server will allow incoming smtp from. I would then like to reject emails coming from all other ip addresses. My router is a 2wire AT&T dsl basic router.

How do you set exchange 2003 to only accept incoming email on port 25 from specific ip range?

Hardware-based firewalls provide more sophisticated protection for inbound and outbound traffic than the simple Windows software firewall or the basic NAT firewalls found in routers. These devices implement techniques such as stateful packet inspection, deep packet inspection, and content filtering; and may include built-in antivirus and anti-malware protection.

Hardware Firewalls

Exchange is the server side of a collaborative application product that is part of the Microsoft Server infrastructure. Exchange's major features include email, calendaring, contacts and tasks, support for mobile and web-based access to information, and support for data storage.

Exchange

Various techniques are used to prevent email spam (unsolicited bulk email). No technique is a complete solution to the spam problem, and each has trade-offs between incorrectly rejecting legitimate email (false positives) vs. not rejecting all spam (false negatives) - and the associated costs in time and effort. Anti-spam techniques can be broken into four broad categories: those that require actions by individuals, those that can be automated by email administrators, those that can be automated by email senders and those employed by researchers and law enforcement officials.