Description
Currently, there is no way to prevent a user from creating items via email. There’s the ability to restrict board members from creating from the “new” button already, to require users to create via Forms, however, users can bypass this by creating via email.
The recommendation to clone the board to get a new email address only works if the users are external, but every board member can view the email address.
A quick fix could be to control the visibility of the email address dropdown under Settings to board owners versus members under the General Board Permissions.
What are you trying to achieve
Consistency of the workflow automation by restricting users to create items via Forms only.