Quick note -- Please don't keep double posting your messages in the forums, it makes it tougher to keep a track of the threads.
Another question, which version of qcodo are you using? Please note that there have been some fixes and things with the QEmailServer class in the 0.4.x releases, several of them in fact. Not sure if any one of them might resolve your issue or not. See the Changelog for more info.
In terms of using gmail to send out -- you can do it, but note that QEmailServer only makes unencrypted connections. I believe Gmail is now enforcing SMTP over SSL. If not, then you should be able to use it just fine, just be sure to provide your login information to QEmailServer.
Lastly, for questions involving SPAMAssassin, I would suggest that you go to hte Spam Assassin website for more info with that. If you are having issues with it, and if your smtp server is truly an internal-only smtp server used to send out email from your website, why not just go ahead and disable it?