I have a SharePoint Online site I administer for my company. The business users want to grant access to their site to external users from a variety of small professional architect companies (usually 5-10 employees in each, but about 40 companies.)
Most of the companies have their own email domains, such as email@example.com. Instead of maintaining a list of 200-400 individuals that come and go, how can I grant access to anyone in the company? In short, instead of allowing firstname.lastname@example.org, I want to allow anyone from smallarch.com to have access.