Cannot Telnet to port 25 from Vista

I cannot seem to connect to an external mailserver through port 25 from my

Windows Vista machine. The problem is also from a couple of VM's whih reside

on that same desktop.

I've checked the following things:

Turned of the Vista Firewall

I can connect to the same external mailserver from another machine on my

network

I do not have any Anti virus installed on the Vista machine

I can telnet to other ports (for example port 80) on that same mail server

from Vista

So in short. My ISP isn't blocking port 25

Anti virus is not blocking port 25

Telnet is working

The remote host is reachable from Vista

I have Windows Vista Ultimate SP1

I hope you can help me on this one.