Yes - you can use
James which is an open source SMTP server. Better though is
Dumbster which is intended as a test harness for programming with SMTP, so you can test that at least your code is working before having to deal with all the infrastructure issues.
Speaking of which, if there is a proxy between you and your SMTP server that could well be the problem, since proxy servers only tend to support HTTP. Check out the
Java Mail FAQs for more detail.