So I have a client that uses MS Exchange 2010 and the network sits behind a Cisco Pix. This server is unable to email anyone with an MSN account. At first I thought it was a blacklist issue, but confirmed it was not. Then I check my queue and realized that all messages get stuck when addressed to msn.com, then I did a telnet to mx1.hotmail.com 25 and was able to connect but when I tracert 188.8.131.52 i get nothing but timeouts, I went to another mail server also behind a pix and I have the same issue. Is this just a coincidence? I have multiple mail servers behind ASAs and don't have this issue, is there something on the PIX causing this?