Is my sender an open relay?

[mailmole]

Hi everyone!
I was thinking the other day - how can I exactly know if my SMTP is prone to any sort of vulnerabilities, as considerable as being an open relay?
After some digging I ran into the suggestion to use telnet IP 25. However, I am not sure if its exact purpose is to check whether the server is an open relay. When I ran it, it gave me no error, which would mean my server is an open relay.
However, when I ran a check on MXToolbox, the report said it wasn't an open relay.
So which one is correct? And, what's the best method to check on those things?

 

[Amit]

1. Check whether you running command on localhost or from the remote machine ?
if localhost then it's okie . if not then you have opened the connection from every ip .

2. Check IP restriction setting for the MTA which you are using ?
This might solve your thing .