This is useful because we posted our online form on social media. We are not able to reach out to everyone who has seen the post with a mass email letting them know that the event is sold out and the form is not longer active. It would be good for our relationship to potential donors to provide them with a message, rather than simply an "error 404" page if they attempt to purchase tickets after they have been sold out. They may just be confused and frustrated to see the error message.