Thanks to MS's thick-headed naming dept, the usual potential confusion exists. If I interpret you correctly:
You do not use the Outlook client in your Office 2010—or it's not relevant here.

Does that imply that your other accounts do not have the problem you describe?

If that's the case, compare the settings between the 'bad' account and the 'good' accounts—that should identify what's amiss.
Tip: take screenshots or phone photos of the settings if you don't have 2 monitors, makes checking easier.