How to Secure Microsoft Teams Channel Email: A Step-by-Step Guide
Imagine getting this exam question in your Microsoft 365 certification test. You need to make sure Teams channels only accept email from your company domain (contoso.com) and a trusted partner domain (fabrikam.com). Where do you go first?
If you picked org-wide Teams settings, you’re right. Here’s how to set it up.
Why Channel Email Security Matters
By default, Teams channels can receive email from any address. That can open the door to spam or phishing attempts. Locking this down keeps your channels safe and your team focused.
Where to Make the Change
- Open the Teams admin center.
- Go to Org-wide settings > Teams settings.
- Find the Email integration section.
This is where you control channel email security.
Setting Up Domain Restrictions
In the Accept channel email from these SMTP domains field, type:
textcontoso.com;fabrikam.com
Use a semicolon to separate domains—no commas or spaces.
If you prefer PowerShell, run:
powershellSet-CsTeamsClientConfiguration -RestrictedSenderList "contoso.com;fabrikam.com" -AllowEmailIntoChannel $true
After you save, it takes about an hour to apply across your tenant.
How It Works
Once enabled, Teams will block email from any domain not on your list. Team owners can’t override this, so you get true tenant-wide control.
Why Other Settings Don’t Work
- Azure AD External collaboration settings manage guest access, not channel email.
- Exchange accepted domains define mail routing for Exchange, not Teams channels.
- Global Teams policies handle user permissions for meetings and messaging, not email domain filters.
Extra Tips for Stronger Security
- Turn off email integration entirely if you don’t need it. That fully closes the channel email feature.
- Enable multi-factor authentication for every Teams user.
- Regularly review guest access and team membership.
- Disable unused cloud storage integrations to prevent data leaks.
Advanced Controls
For tighter security, use the Tenant Allow/Block List in the Microsoft Defender portal. There you can block specific domains across all Microsoft 365 services and set expiration dates on blocks.
The Bottom Line
Securing your Teams channel email is quick once you know where to look. The org-wide Teams settings give you the power to allow only trusted domains. Make this simple change today to keep your Teams channels clean and secure.
