Invalid URL '#' in an RSVP link

For school administrators using GiveCampus Outreach. Controls can differ between the classic email editor and the newer Composer editor.

A literal # is a placeholder, not the intended event-registration destination. Set the RSVP link/button to the correct event URL or supported event-link token, then preview the generated recipient link and revalidate. The validator has special handling for recognized Composer placeholder buttons; that exception does not make every inline # link valid or usable. Do not remove validation without fixing the actual destination.