Forbid message edit

Hello Kyle and JoomlaPolis team, 
It's a bit late to do so, but I'd like to take this opportunity to wish you all the best for the New Year!
I noticed that my users can edit there messages even after they are sent. How can I forbid this? I couldn't find any option to do so.
Thank you!

They can only edit the message after it has been sent if it hasn't been read. There's no functionality to turn this off, but again they can only edit it if it hasn't been read yet.

Ok but there's a copy of the message in the e-mail notification. What about it?
Also, how can I remove the following options:
-report message
-delete message

Thank you

Ok but there's a copy of the message in the e-mail notification. What about it?

Nothing I can do about that. Suggest turning off including the message in the notification. It's default disabled because it poses potential privacy issues.

Also, how can I remove the following options:
-report message
-delete message

Neither can be disabled. Reporting is to allow users to report abuse and deleting is so they can of course delete their messages. Why do you need to disable these?