Winserver2012 mail delivery failure,
Have three ali cloud server, all Winserver2012, using the same program, in a table can normal email, other two failures,
Telnet server port 25, normal email which it is to be able to connect, the failure of which two (2) there is an error "unable to open the connection to the host, in the port 25: connection failure",
Shut the firewall, open port 25 also not line,
Please directly, thank you!