You can use the External Sharing features in Microsoft 365 to securely collaborate with external users, even if they don’t have an Azure Active Directory account. You can share Teams channels, SharePoint sites, and OneDrive files. In this article, we’ll look at how to enable and set up external sharing in the Microsoft 365 tenant.

You can use the external sharing feature in the following services in Microsoft 365:

• SharePoint Online
• OneDrive for Business
• Microsoft Teams
• Microsoft 365 Groups

External sharing is enabled for the entire SharePoint Online environment and all sites by default. You can configure external sharing settings at both the organization and site levels.

Open the SharePoint Admin center and expand the Policies > Sharing section.

There are two sliders available here, one for SharePoint and one for OneDrive. The following values are available:

• Anyone — users can share files and folders using links that don’t require sign-in (selected by default);
• New and Existing guest — to access the files, guests must sign in or provide a verification code;
• Existing guests only — guests are required to be added to the organization’s Azure AD;
• Only people in your organization — external sharing isn’t allowed. Your files can only be accessed by users within your organization.

Below are some additional external sharing options:

• Limit external sharing by domain — you can specify a list of trusted domains from which users can share files;
• Guest must sign in using the same account to which sharing invitations are sent;
• Allow guests to share items they don’t own;
• Guest access to a site or OneDrive will expire automatically after this many days;
• People who use a verification code must re-authenticate after this many days.

To share a file in SharePoint Online:

1. Open your site and select the file;
2. Click the Share button and select the user you want to share the file with;
3. Here you can choose whether this user can Edit, View or Review the file;
4. Click Send to send your external partner the link to the shared file. The user you specify will receive an email with a link to your document.

Similar options for sharing files with external users or users in your organization are available in OneDrive.

Note. See the article at the link to learn how to create shared channels in Microsoft Teams.

If file sharing is not allowed at the organization or site level, an error will be displayed:

Your org doesn’t allow sharing with these people. To continue sharing, remove the highlighted recipients.

Or:

Your organization’s policies don’t allow you to share with these users. Go to External Sharing in the Office 365 admin center to enable it.

An error may occur when sharing a document:

This link won’t work for people outside of your organization.

In this case, to grant an external user access to the file via a link, you need to change the Select the type of link that’s selected by default when users share files and folders in SharePoint and OneDrive option in SharePoint Admin Center > Policies > Sharing. Change the default mode from Only people in your organization to Anyone with the link.

You can set the external sharing parameters individually for each collection of SharePoint sites:

1. Open the site settings and go to the Policies tab;
2. Click Edit in the External Sharing section;
3. This is where you can change the settings for external sharing for your site;
4. Most Site Policy settings are set to the Same as organization-level setting.
   

If the global policy settings and the site-level policy settings are different, files in SharePoint and OneDrive are subject to the most restrictive settings, which override the external sharing policy settings.