Exchange server 2003 blocks emails from wells fargo rep - i deleted all anti-spam software - what else to do?

I have no anti-spam software - in exchange server I have no content filtering. My Cox cable internet is pointed to my server. I am getting tons of spam BUT None from Wells Fargo or other emails from a couple of my best clients. I have created new emails on cox.net and get emails from the aforementioned people on my house emails instead of my work email on exchange.