Quote:Original post by Evil Steve
This may be related - I had some similar problems when I wrote a SMTP mail sender in C++. Hotmail's mail server IP isn't the same as it's web server IP.
When you do a DNS lookup normally, you're doing a A record lookup, which returns the IP of the Hotmail web server. You need to do an MX lookup to get the IP of the mail server.

What's probably happening is you're trying to send mail to Hotmail's web server IP rather than the SMTP server IP.