Outlook 2003 outgoing mail being sent as spam?

I have office 2003….it was working all fine and good till like Monday….now all the emails I send to myself or anyone else are going to spam…somehow they are all going out as spam…but ONLY through outlook. I tried through Thunderbird and they are fine…I try from the comcast site itself and it is fine…..there is something wacky in outlook that is making it go out as spam……..anyone have any ideas on how to fix this??