Hm, this could start becoming an interesting weekly thing. Friday’s cool API of the day is SHSetUnreadMailCount():

API HRESULT SHSetUnreadMailCount(LPCTSTR pszMailAddress, DWORD dwCount, LPCTSTR pszShellExecuteCommand);

How it works: Basically, you pass in a unicode string that contains the current user’s email addres, along with the number of unread messages. The last parameter, pszShellExecuteCommand is the command that is passed to ShellExecute() to start the email application for the particular address.