Originally Posted by till
If you connect to your server with telnet on localhost, how much time does it take if you get the server greeting?
Another possibility might be that your postfix tries to resolve the domain of the monitoring serveice and thsi fails or took longer then 20 seconds.
I have setup a telnet connection.
It took 28 seconds to establish the connection,
which is 8 seconds more then the 20 seconds i mentioned before.