I have a Windows 2003 Small Business Server (SP1) running Exchange server that cannot receive email from comcast.net email accounts. I have uninstalled the Policy Patrol Spam software from the server and checked to make sure that the comcast.net domain is not blocked. Comcast.net messages do not appear in Message Tracking. I have checked with Comcast and they have assured me that they are not blocking the domain. Our IP address is not on any SPAM lists and there is a correct reverse DNS entry setup with Verizon our ISP. We are able to receive email from other domains without any problems. Microsoft Exchange troubleshooting assistant is pointing to an outside the server problem. I'm at a lost where else to look for the problem and I don't want to re-install the OS unless I have to.