Lol, helpdesking over the phone is so much fun. My dad just called me to see if I could figure out why his mail stopped working. He could still surf the web, so the link itself wasn't totally dead. We quickly went over some account details, but it all checked out, yet no connection to the mail server.
A telnet session to the server failed as well, even though I had no problem connecting to it, coming from an IP address that doesn't even belong to the provider my dad uses. When I asked more questions as "what caused your mail connection from failing" and "did you change anything lately" the answer I got at least gave me a clue : oh yeah, I used some tune-up utility to get rid of old crap and make my machine faster.
I told him to have the program undo whatever it fucked up and then try the telnet connection again. There is little point in reinstalling his mailprogram if even a basic function like telnet ain't able to get a connection. His next computer comes with only webmail, I joked ;)