Body
In SharePoint, sharing is implemented at two levels:
- Organization Level
- For any external sharing to be allowed, it has to be enabled by OU.
- Site Level
- Once enabled across the organization, external sharing can be restricted on a site-by-site basis. Global or SharePoint admins in Microsoft 365 can change the external sharing setting for a site, but site owners cannot do this.
In some cases, there might be a mismatch between these two levels. In that case, the more restrictive of the two policies is the one applied.
Types of External Users
In SharePoint, if you share with a user who is not in the OU directory, they are sent a one-time code that they can use to verify their identity. The next aspect of sharing to understand is that SharePoint supports four basic options when it comes to external sharing and that each option allows your files to be accessed by different types of user:
No External Sharing:
The default option for communication and classic SharePoint sites. If this option is enabled, it will prevent any site users from sharing any site content externally. This can be a good option for sites that only your team need to have access to. To use this option, go to your SharePoint admin center, and in the left pane under Sites select Active sites. Select the proper site, and then click Sharing. Select the Only people in your organization option and select Save.
Authenticated: Existing Guests
Existing Guests allows external sharing with users who already appear in your Azure Active Directory. External users will appear here if they have previously accepted sharing invitations, or if you manually added them in the Azure Portal. To use this option, go to your SharePoint admin center, and in the left pane under Sites select Active sites. Select the proper site, and then click Sharing. Select the Existing guests’ option and select Save.
Authenticated: New and Existing Guests
New and Existing Guests allows new users to access your files via an invitation link. To use this option, go to your SharePoint admin center, and in the left pane under Sites select Active sites. Select the proper site, and then click Sharing. Select the New and existing guests’ option and select Save. As an administrator, you can share a site with new users, and site users can share any files held on this site. When they share a file, the new user will receive an email invitation with a link. They will then either sign into their Microsoft account or enter a verification code. If they use a Microsoft account, they will be automatically added to your Azure Directory. If they use a verification code, they won’t be, and they will have to use a code every time they want to access files.
Anonymous Sharing:
If you use this option, anyone with a link will be able to view and edit the relevant files. This can be a quick way of giving external users access to your files, but you should be very careful when using it, because you will have little oversight as to how your files are being accessed, used, and further shared. To enable this option, go to your SharePoint admin center, and in the left pane under Sites select Active sites. Select the proper site, and then click Sharing. Select the Anyone option and select Save.