MAPI sent mails do not show up in Outlook

I tried to execute a mailmerge in windows 7, using Microsoft Outlook 2007 (which was also set as the default program for whatever it is capable of, including MAPI, using the \default programs\ dialoge in the configuration.) and MS Word 2007. Although both windows/winword and outlook do not present me with some error, I would say the e-mails are sent.

But outlook doesn't have them in it's outbox, nor sent folder, nor were the e-mails recieved. The e-mailadresses were correct, moreover I used the same datasource to succesfully complete another mailmerge, earlier.

I also have thunderbird installed, but it is not set as the default email/MAPI program.

Is there anything I missed checking?

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