Quick description

Ever been in a Teams chat with someone from another tenant and hit the classic moment:

"Can you just email the file instead?"

Yeah… let's not do that.

With one small policy change, Teams can happily share files directly in chats with external users. No Outlook detours required.

What does this change?

This updates the Teams Files Policy (in this case the Global policy) to allow file sharing in chats that include external participants.

In other words:

If someone from another tenant joins a Teams chat with you, you can drop files directly in the conversation — just like you would with internal users.

What can you do afterwards?

Once enabled, you can:

• Share files directly in 1:1 chats with external users
• Share files in group chats that include external participants
• Collaborate faster with partners, vendors, and consultants
• Avoid the dreaded "I'll just email it instead" workflow

Basically: Teams chats start behaving like you always expected them to.

What might affect whether it works?

Turning on the policy is only one piece of the puzzle. A few other settings can influence whether file sharing actually works.

Things to check if it doesn't behave as expected:

• External Access in Teams
  If external access is disabled, users from other tenants can't properly participate in chats.

• SharePoint / OneDrive external sharing settings
  Files shared in chat are actually stored in OneDrive behind the scenes.
  If external sharing is restricted there, the upload or share might fail.

• Sensitivity Labels / Microsoft Purview
  Labels or DLP policies may block external sharing depending on classification.

• Conditional Access policies
  Device requirements or session restrictions might affect file access.

• Client caching / policy propagation
  Policy changes can take a little while to propagate. Sometimes a Teams restart helps.

PowerShell

Below is the quickest way to enable the setting.

# ------------------------------------------------------------
# Rights required
# ------------------------------------------------------------
# Teams Service Administrator
# Global Administrator
# or equivalent role with permission to manage Teams policies

# ------------------------------------------------------------
# Connect to Microsoft Teams
# ------------------------------------------------------------
Connect-MicrosoftTeams

# ------------------------------------------------------------
# Enable file sharing with external users in chats
# ------------------------------------------------------------
# This updates the Global Teams Files Policy so users
# can share files in chats that include external participants.

Set-CsTeamsFilesPolicy `
    -Identity Global `
    -FileSharingInChatsWithExternalUsers Enabled

# ------------------------------------------------------------
# Verify the configuration
# ------------------------------------------------------------
# This confirms the policy setting is enabled.

Get-CsTeamsFilesPolicy -Identity Global |
Select-Object Identity, FileSharingInChatsWithExternalUsers

# Expected output:
#
# Identity   FileSharingInChatsWithExternalUsers
# --------   -----------------------------------
# Global     Enabled

Final thoughts

Sometimes the difference between "This collaboration is easy" and
"Can you just email the file?"

…is literally one PowerShell command.

Flip the switch, keep the conversation in Teams, and let files travel across tenants the way they probably should have all along.