I have no idea about nginx, it's a new installation I have the following parameters in firewall..
# Mail SMTP:25
-A INPUT -p tcp --dport 25 -j ACCEPT
-A OUTPUT -p tcp --dport 25 -j ACCEPT
# Mail POP3:110
-A INPUT -p tcp --dport 110 -j ACCEPT
-A OUTPUT -p tcp --dport 110 -j ACCEPT...