We need to share a folder containing several Excel files with someone outside our organization. Sharing works for our accountant, but this particular user's company does not provide Microsoft software or accounts, and they appear to use a free office suite instead.
Guest access and sharing with specific people have not worked because the user cannot complete the Microsoft account or MFA steps. Our software provider's support team has not been able to resolve it either, so management is considering purchasing licenses for the user.
Would SharePoint Plan 1 be enough for this? Could the user access the folder through a web browser and edit the Excel files there, or would they need Microsoft software installed? Can they authenticate using the Microsoft Authenticator app or an email one-time passcode without having a Microsoft 365 subscription? Are there other practical ways to share the files securely?
5 Answers
Another fallback is to export copies in a format their existing suite supports, such as OpenDocument Spreadsheet, and use an approved file-sharing service. That can introduce compatibility and security issues, though, so browser-based Excel access with properly configured guest authentication is usually the better first option.
Before buying a license, try adding the person as an Entra ID guest using their normal email address. A guest account does not automatically require them to have a paid Microsoft subscription. If your policy permits it, email OTP is often the simplest authentication method. Buying a SharePoint license for the external user may not solve an authentication policy or sharing-configuration problem.
An external guest can usually access the SharePoint folder and open the workbooks in Excel for the web, without having desktop Office installed. Whether they can edit depends on the sharing permissions and your tenant settings. Their existing office suite may not be relevant if they use the browser version, although advanced Excel features may not work perfectly.
The “Anyone with the link” option is controlled by organization and site-level sharing settings, so it may be intentionally disabled. It is also less secure because the link itself becomes the credential. A guest invitation with email OTP is preferable for sensitive business files. If the user needs ongoing access and support, formally onboarding them as a contractor and assigning the appropriate license may be cleaner, but confirm the licensing and security requirements first.
They do not necessarily need a Microsoft account or Microsoft software to be added as a guest. Invite their existing work email address, then use email one-time passcode authentication if it is enabled in your organization. They should receive a code by email and use that to access the shared files. Conditional Access should generally require multifactor authentication rather than a more restrictive authentication-strength policy for this scenario.
That may be the part we were missing. I’ll check whether email one-time passcode authentication is enabled and whether our current MFA policy is blocking the guest.