Allowing access to my SharePoint Site for external users

To let external people access a SharePoint site and share files, two levels of settings must allow external sharing: at the organization level and at the site level. After that, site permissions and sharing behavior can be configured.

1. Ensure external sharing is enabled for the organization
   • A Microsoft 365 Global Administrator or SharePoint Administrator must turn this on.
   • In Microsoft 365, external sharing is controlled centrally; if it is disabled, adding external members at the site will fail.
   • Admins can enable external sharing at the organization level from:
     • The SharePoint admin center → Sharing page, or
     • Microsoft 365 admin center → Org settings → SharePoint.
   • The organization-level setting defines the maximum allowed sharing; individual sites can be more restrictive, but not more permissive.
   • Recommended org-level option for your scenario: New and existing guests, which allows inviting people outside the organization who authenticate and are added as guests.
2. Enable or adjust external sharing for the specific site
   • A SharePoint or Global admin must:
     1. Go to Active sites in the SharePoint admin center.
     2. Select the site that should be shared externally.
     3. On the Settings tab, choose More sharing settings.
     4. Under external sharing, select an option that permits external users (for example New and existing guests or Anyone, depending on how open the site should be).
     5. Optionally configure Limit sharing by domain and guest access expiration if needed.
     6. Select Save.
   • If external sharing is later turned off at the organization level, all external links to this site stop working until it is re-enabled.
3. Decide how external users should access the site There are two main patterns: a. Add external users as site members via Microsoft 365 group
   • On the site, select Settings → Site permissions.
   • Choose Add members → Add members to group.
   • Enter the external users’ email addresses and save.
   • These guests are added to the Microsoft 365 group and to the Site members permission group by default, so they can edit the site and use group resources (conversations, calendar, etc.).
   b. Share the site without adding to the Microsoft 365 group
   • On the site, select Settings → Site permissions.
   • Choose Add members → Share site only.
   • Enter the external users’ email addresses.
   • Use the drop-down to choose the SharePoint permission level (for example, Edit or Read), then select Add.
   • This gives them access to the site but not to the Microsoft 365 group resources.
4. Control what existing members can share
   • As site owner, open Settings → Site permissions → Change how members can share.
   • Under Sharing permissions, choose how broadly members can share:
     • Allow owners and members to share files, folders, and the site; or
     • Allow only owners to share the site; or
     • Allow only owners to share anything.
   • Under Access requests, turn Allow access requests on if external users should be able to request access when they hit a blocked page, and specify who receives those requests.
5. Understand sharing options and security impact
   • Site-level external sharing options:
     • Anyone: Allows site owners to share the site with people who authenticate, and lets users choose whether file/folder links require sign-in or not. “Anyone” links can be forwarded freely.
     • New and existing guests: Allows sharing with people outside the organization who must sign in and are added to the directory.
     • Existing guests: Only guests already in the directory can be used.
     • Only people in your organization: No external sharing.
   • For a collaboration-focused site with remote contributors, New and existing guests is typically appropriate.
6. Best practices to avoid accidental oversharing later
   • If the entire site is intended for external collaboration, keep sensitive content in a different site that is not shared externally.
   • Consider creating separate sites (not subsites) for different external projects so each has its own external sharing boundary.
   • Remember that if the whole site is shared with an external user, that user can browse, search, and edit content according to the assigned permission group, and will appear in the People Picker for others to grant additional permissions.
7. If external sharing is disabled or later turned off
   • When external sharing is turned off globally, external users lose access and guest links stop working. If it is turned back on, previous links and permissions resume working.
   • To permanently remove an external user’s access, remove them from the external users list in Microsoft 365 Service Settings or from the site’s permission groups.

Following these steps ensures that external collaborators can access the SharePoint site and share files as intended, assuming the Microsoft 365 tenant’s admin has enabled external sharing at the organization and site levels.

References:

• B2B Sync for SharePoint and OneDrive
• Manage sharing with external users in Microsoft 365 Small Business
• Change the sharing settings for a site
• Change a site's title, description, logo, and site information settings
• Set up and manage access requests