🔐 Invitation Error: The following email addresses do not belong to an accepted domain

Summary

This article explains why Mattermost may display the error message "The following email addresses do not belong to an accepted domain: a@xyz.com. Please contact your System Administrator for details." when inviting users, and how to check and resolve the issue using either the System Console or the config.json file (for AWS ECS or air-gapped environments).

📌 When Does This Happen?

This error appears when:

• The email domain of the user being invited is not in the allowed domain list, either at the team level or the system-wide level.

• The Mattermost deployment has email domain restrictions enabled for new account creation or team membership.

✅ How to Resolve

Option 1: Use the System Console (Recommended)

No restart required.

1. Team-Level Restriction

   • Go to: System Console > User Management > Teams

   • Click the team in question.

   • Check: Allow only users with a specific email domain to join this team

   • ➤ If enabled, make sure the domain (e.g., example.com) matches the invited user's email address.

2. System-Level Restriction

   • Go to: System Console > Authentication > Signup

   • Check: Restrict account creation to specified email domains

   • ➤ If enabled, confirm the domain is listed properly (e.g., example.com)

⚠️ Domain entries are case-sensitive and must match exactly.

Option 2: Check via config.json (For ECS or air-gapped setups)

You can verify system-level restrictions by inspecting the following section in your config.json file:

"TeamSettings": {
    "RestrictCreationToDomains": "example.com"
}

✅ Note: The global config does not contain per-team restrictions. Team-level domain restrictions must be managed through the System Console.

ℹ️ Additional Notes

• If the RestrictCreationToDomains value is an empty string (""), there is no system-wide domain restriction.

• If the issue persists after updating domains, try reloading the config via System Console or restarting the server if config changes were made directly in config.json.