fix teams addin:

- Close Outlook and Teams

- Uninstall Microsoft Teams and Teams Machine-Wide Installer

- Under %localappdata%\Microsoft delete the folders: SquirrelTemp, Teams, TeamsMeetingAddin and TeamsPresenceAddin

- Download and re-install Microsoft Teams


[[https://learn.microsoft.com/en-us/answers/questions/291072/outlook-keeps-disabling-the-teams-plug-in|Quelle]]

registry:

- Launch RegEdit.exe

- Navigate to HKEY_CURRENT_USER\Software\Microsoft\Office\Outlook\Addins

- Verify TeamsAddin.FastConnect exists.

- Within TeamsAddin.FastConnect, verify LoadBehavior exists and is set to 3.

- If LoadBehavior has a value other than 3, change it to 3 and restart Outlook.

- For more details about how to troubleshoot this issue, you can refer to:
https://learn.microsoft.com/en-us/microsoftteams/teams-add-in-for-outlook#troubleshooting

If the add-in has been disabled, you can try to follow these steps to prevent it:

- Open Run, type “regedit” to open the registry editor.
- Go to “HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Resiliency” (16.0 for Outlook 2016)
- Delete the DisabledItem if there is.