Why can't I add an external user to SharePoint Group via Outlook?

Question

• I am trying to add 3 users to a SharePoint Group. All users are from the same external domain. I have confirmed each user does have an Office 365 account associated with their email addresses.
• I get the following message: "The following person couldn't be added. Retry."
• I am trying to do it via Outlook (web-based) / Groups / Add Members
• I have updated the permission settings in Admin / Azure Active Directory / External Collaboration Settings
• I have updated the permission settings in SharePoint Admin / Sharing & Sites. I have tried this with both Anyone with the link can access set, as well as New & Existing Guests Set. I have made sure all sharing settings w/ outside domains are correctly applied.
• The SharePoint site is still listed as a "Private Group" - not sure if this has anything to do with the issue
• I have also added these email addresses as mail contacts in Exchange with no luck

Why am I unable to add these external users? I added someone else with a Gmail account, as well as a few people from another organization w/ their own domain, so I'm not sure what the issue is.

Answer 1

Hi @HC2 ,

Per my test, if I set the collaboration restrictions only to the specified domains, then add guest users who do not belong to the target domains, the issue occurs:

We suggest you check the restricted domains again or allow invitations to be sent to any domain (most inclusive), save the change, add the external user again to compare the result.

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