Usermin : "From" field from "Compose Email" should not be editable

The "From" textbox field from "Compose Email" is editable by default and this could be a potential bug as any users can change the "From" text field and send the fake emails. Usermin also doesn't authenticate it before sending emails.

The issue is that Usermin doesn't restrict to just mail aliases but one can enter anything in the "From" textbox no matter if the email account exists or if it's email alias with the same mailbox.

For ex: One can type "does-not-exists@domain.com" or "anything@example.com" and it does send the email. This is something I would like to stop so that the shared hosting user should not be able to send emails on behalf of other users email id.

Screenshot:

Here is a screencast: https://www.useloom.com/share/4a63da0c79f24897b8eef3526a8e18e4

How do we make this field read-only? Or dropdown for email alias? Or even hidden if possible?