The fact that I can't telnet to any outside SMTP server removes any mistakes I may have made on my end anyway, since it doesn't involve the SMTP server.
Try http://ipaddr.ca and tell us what your IP and reverse DNS are? Some of us (including me) have access to non-public databases that might tell me what's going on with your IP address' "reputation". Again, email directly if you don't want to share it on a public mailing list.