I was recently having some problems with setting up POP email at home and I wanted to verify what port were open and I realized that TELNET did not appear to be installed. As we are not using Vista at work I do not tend to have much need to dig past the obvious stuff for very long.

Apparently Vista installs without telnet by default and you must explicitly enable it:

• Open ‘Control Panel’ and select ‘Programs’.
• In the left column, select ‘Turn Windows features on or off’.
• Check the box next to telnet, and wait...

I ran a quick telnet command (telnet mail.someplace.com 25) that clearly showed that port 25 was being blocked by my cable provided router. After asking them to open it I was sending emails like it was going out of fashion.