Do I need to license external users for SharePoint Server?

No separate per-user license is needed for external users — Microsoft Product Terms include external user rights with the SharePoint Server license. An external user is defined as someone who is not an employee, contractor or vendor of your organization or an affiliated entity.

The catch: those rights apply to your SharePoint Server, hosting your content for your business. You cannot stand up a SharePoint Server to host content for a third party — that is a Service Provider scenario and requires the Service Provider License Agreement (SPLA).

Still unsure?

Talk to a licensing specialist for a written, signed quote tailored to your environment.