I have a mail server using just the IIS 6.0 SMTP relay. I am trying to mass mail to my customers on comcast, and my mail is not leaving the outgoing queue on it. I have disabled my antivirus. I cannot telnet to mx1.comcast.net on port 25, BUT I can telnet to its IP address. This is not the case with other mail servers like yahoo's. I am not having this trouble on my laptop as I can telnet to mx1.comcast.net and mx2.comcast.net. But I can only use those IPs to telnet to on the SMTP server. Is this possibly keeping this mail in the outgoing queue? I have tried rebooting and restarting the SMTP service. It is an update 2003 Windows server. Thanks!