In an effort to bypass your email filter, spammers often send directly to your mail server.  One solution to prevent them from doing this is to limit what IP's are allowed to connect to your local mail server.  This can be accomplished either by setting up a firewall or by configuring your mail server to restrict what connections are allowed.

Be sure that when configuring your firewall or mail server that all of our filtering server IP's are able to get through.  Or, for Microsoft Exchange users, see our Configuring Microsoft Exchange to only accept email from SpamHero IPs instructions.

Please refer to the Current List of SpamHero IPs document to obtain these IPs.

CAUTION: If you have remote users that send through your mail server you will want to be sure that you do not block their access to send mail.  One common solution is to configure your mail server to allow connections on an alternate port (such as 587).