@iiTsXcept not within Forms, the settings are either that anyone with the link can respond or that only people in your organisation can respond. The way I would handle this would be to have a list in SharePoint of the "allowed" email addresses and use a flow in Power Automate to check if the responder's email is on that list; if it is then do some actions, if it isn't then do some other actions.
Rob
Los Gallardos
Microsoft Power Automate Community Super User
