The mere fact nothing was marked as an answer doesn't mean a proposed solution wasn't correct. People often lack the courtesy to give any feedback, let alone acknowledge correct solutions they've been provided as being an answer. In any event, the OP's particular problem was solved via the solution posted in #4 or #5 above.
Part of the problem may be due to Outlook's security settings. Try installing the 'Express ClickYes' utility available from:
A program is trying to send e-mail on your behalf. Bypass this message with ClickYes..