Ensure that the Profile names for your Outlook Profile and Dimensions email options match.
To check mail profile:
Open Control Panel
Select Mail from the list
Click Show Profiles
See which profiles are in the list
If there is more than 1, then note down the once you log in with, or the one that is selected at the bottom "Always use this profile:"
To check Dimensions settings:
Click System
User Records
Select the affected user from the list and click E-Mail
In the Profile field, enter the name of the profile you found in the previous section
Save your changes
This error can also be caused when the version of Outlook installed is a 64-bit version. See this article for details on how to check. Dimensions will only work with 32-bit versions of Outlook.