Guest Users Cannot Mention User Groups in Mattermost

Problem

Guest users in Mattermost are unable to mention user groups using the @groupname format. While regular members can use and autocomplete group mentions, guest users do not see group names when typing @, and their mentions are not recognized.

This issue can cause confusion or collaboration limitations for teams using guest accounts with restricted access.

Root Cause

By default, the "Group Mentions" permission is not enabled for the Guest role in Mattermost. As a result, guest users cannot use group mentions unless this permission is explicitly granted through the system or team permission schemes.

Solution

To enable group mentions for guest users:

1. Go to the System Console
   Navigate to:
   System Console → User Management → Permissions
2. Edit the Permission Scheme
   • If you use the default System Scheme, click Edit Scheme.
   • If you're using a Team Override Scheme, select it from the list and click Edit.
3. Enable Group Mentions for Guests
   • Scroll to the section for Guest permissions.
   • Enable the checkbox for Group Mentions.
4. Save Changes
   • Click Save to apply the updated permission.
5. Test Functionality
   • Log in as a guest user.
   • Type @ in a message box to confirm group names now appear in autocomplete.