SH Development writes:

I have literally tried every combination of settings in OE and nothing works. What else might I need to enable to get this working?

Using SSL, ports 993, 587 PLAINTEXT.

As others have noted, your MTA handles the connection. I believe Windows XP needs to be updated to the latest service patch to handle SSLv3 disabled sites. Try checking to make sure your Postfix SSL security settings and your WinXP SSL capabilities are compatible.

Joseph Tam <jtam.home@gmail.com>