Please try the following in Outlook 2021 after installing Spamfighter:
- Select “File” in the Outlook main menu.
- Select “Options” at the bottom of the left side menu.
- Click on “Add-ins” at the bottom of the left side menu.
- Click on “Go” next to the “Manage: COM Add-ins”
- Find “SPAMfighter Add-in” in the list, and check the associated box.
- Click on “OK”