I'm running Ubuntu Server 12.04 LTS on several servers on the Amazon Cloud EC2 service. I have successfully installed and configured postfix/dovecot as a secure SMTP server on one of the servers. I can send emails from this server. Eventually I will be relaying to a bulk email service.
My problem is that I want to communicate with this server from one of the other servers in the same security group. I have searched for a solution and found a lot of advice, but nothing complete and comprehensive.
Things I've tried:
telnet ip 25 from remote host - it hangs and never responds
I've added the following
mynetworks = 0.0.0.0/0 [::/0]
to /etc/postfix/main.cf, and restarted postfix with no change
I've used netstat to verifiy postfix is listening on port 25
sudo netstat -plntu; sudo ls -l /proc/11830 | grep exe
tcp 0 0 0.0.0.0:25 0.0.0.0:* LISTEN 11830/master
lrwxrwxrwx 1 root root 0 Aug 21 23:00 exe -> /usr/lib/postfix/master
I can telnet in from the local host.
Can someone help me out here. Is this a conflict under EC2, SSH, postifix, or UBUNTU?
Thanks for your help.