BleepingComputer.com: Outlook sends invisible messages?

A few weeks ago, when I started Outlook without connecting to the Internet, I randomly saw again displaying near "Transmitting" in the status bar of Outlook, "Sending 14 e-mails", which I hadn't composed, the next time starting Outlook a minute later or so, 15 e-mails are displayed to be sent. I am the only person using the PC.

After having done some measures to avoid this with kindly help of "The Panda" - http://www.bleepingcomputer.com/forums/topic231774.html - I chanced to see it again in the status bar some days ago: there are still invisible messages sent from Outlook, respectively it is displayed.

Might there be a bug in Outlook doing something like that? I have read of such a bug doing something like that, but concerning IMAP only (I only have pop accounts). And these message being sent by the bug you can find / make visible with a program like SpyOutlook or another program from Microsoft as far as I know.

Would it be possible to catch such messages? Or to find out their contents, their destination?

Nice greetings, Dirk