If you want to go down that path, see: http://msdn.microsoft.com/en-us/library/aa338201.aspx
Instead of reinventing the wheel, though, I'd encourage you to find whatever your colleague was using.

If you need more help with implementation, Id suggest asking here:
https://www.msofficeforums.com/outlook/
or at:
http://answers.microsoft.com/en-us/office/forum/outlook

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]