Check Mail Port Connections with netstat

A good way to check the connectons to mail ports is to use netstat:

# netstat -anp | grep :25
tcp        0      0 0.0.0.0:25              0.0.0.0:*               LISTEN      2170/master
tcp6       0      0 :::25                   :::*                    LISTEN      2170/master
# netstat -anp | grep :465
tcp        0      0 0.0.0.0:465             0.0.0.0:*               LISTEN      2170/master
tcp6       0      0 :::465                  :::*                    LISTEN      2170/master
# netstat -anp | grep :587
tcp        0      0 0.0.0.0:587             0.0.0.0:*               LISTEN      2170/master
tcp6       0      0 :::587                  :::*                    LISTEN      2170/master