Testing emails using telnet

When your client can't send/receive emails, but the server is up and running and there are no problems on the administrators side:

You need to telnet the email account to see if there is a problem:

Start - run... - telnet  - mail.yourdomainname 25 (outgoing)/110 (incoming) (enter) - user username (enter) - pass yourpassword (enter). If everything is fine then you can type in - list (enter) this will list your emails that you have received that are on the server.

If everything is fine - then the problem is your client/owner of the email address could have a virus or be behind a firewall or proxy