Share a single document with external user in Microsoft Teams

Guest Access in Microsoft Teams is a great way to collaborate with external Office 365 users in chat, files and existing tabs. Sometimes you may want to collaborate on a single document with an external user without giving them access to your entire team. Turns out, this is disabled by default.

You need to enable it via SharePoint PowerShell, here is how

Connect to SharePoint Online via PowerShell
- Download the module here: https://www.microsoft.com/en-us/download/confirmation.aspx?id=35588
- $orgName=”<your tenantname>”
- Connect-SPOService -Url https://$orgName-admin.sharepoint.com -Credential $userCredential
list all site collections for your Office 365 Groups and Teams
- Get-sposite -template GROUP#0 -includepersonalsite:$false
Copy the URL you want to change
Run the following command to make the change
- Set-SPOSite -Identity https://tenantname.sharepoint.com/sites/NewTeam -SharingCapability ExternalUserAndGuestSharing
- The new sharing capability is called ExternalUserAndGuestSharing
  - External user sharing (share by email) and guest link sharing are both enabled
- The default value is ExistingExternalUserSharingOnly
  - Allow sharing only with the external users that already exist in your organization’s directory

Now you are able to in to a document, click the sharing button, choose specific users and invite those you want to collaborate with on this specific document. It is important that you choose the option “only the people you specify”, then and only then will they be able to work with the document in their desktop client