This error may be triggered by different types of problems. It can occur when your default email client is set to a program that does not support Extended MAPI.
If this is the case, see if temporarily setting it as the default client fixes the issue and restart Aid4Mail. The instructions on how to change the default email client are below:
In Windows 10, search for "default programs" in the search bar next to the Start Button and select the "Default Programs" desktop application.
Then click on the application under "Email" and select Outlook.
In Windows 7, follow the steps on this video tutorial to set your default email client:
If the above solutions do not apply or do not work, see if rebooting your computer fixes the issue.
Should you require any assistance, please don't hesitate to contact the help desk.