I have postfix running on Ubuntu 12.04 and mails are sent without issues but from past few days have issues only while sending mail to gmail mail servers
telnet gmail-smtp-in.l.google.com 25
Connected to gmail-smtp-in.l.google.com.
Escape character is '^]'.
It just hangs there and connection closed by foreign host.
But do not have any issues sending to yahoo, hotmail etc
IP address is not listed in any of the blacklists.