Connect-MicrosoftTeams
Set-CsTeamsFilesPolicy -Identity Global -FileSharingInChatsWithExternalUsers Enabled

The problem

You've probably seen this before.

You're chatting with someone from another tenant in Teams and want to share a file.

Then Teams politely tells you NO.

So the conversation quickly becomes:

"Can you just email the file instead?"

Which is exactly the kind of workflow Teams was supposed to replace.

The fix

Teams actually supports file sharing in chats with external users --- it just isn't always enabled.

By updating the Teams Files Policy, you allow users to drop files directly into chats that include people from other tenants.

After enabling this setting, users can:

• Share files in 1:1 chats with external users
• Share files in group chats with external participants
• Collaborate without falling back to email

Exactly how chat collaboration should work.

PowerShell

All it takes is one setting.

# Requires:
# Teams Service Administrator or Global Administrator

Connect-MicrosoftTeams

Set-CsTeamsFilesPolicy `
    -Identity Global `
    -FileSharingInChatsWithExternalUsers Enabled

Optional sanity check:

Get-CsTeamsFilesPolicy -Identity Global |
Select Identity, FileSharingInChatsWithExternalUsers

If it still doesn't work

This setting is only one piece of the puzzle. File sharing can still be affected by:

• External Access in Teams
• OneDrive / SharePoint external sharing settings
• Sensitivity labels or DLP policies
• Conditional Access restrictions

But in most environments, enabling this policy is the missing piece.

Final thought

Sometimes improving collaboration across tenants sounds like a big project.

Sometimes it's just:

Set-CsTeamsFilesPolicy -Identity Global -FileSharingInChatsWithExternalUsers Enabled

And suddenly nobody has to say
"I'll just email it instead."