How do I preserve a message template?

Content

Hello,

Is there a way to allow agents responsible for doing mass mailings to use a message template for their mailings and modify the message in the mailing, but not modify the message template?  In the step where the agent is supposed to "Copy Content" apparently some of them are changing the original template when creating a mailing. 

If I remove the Administrative permissions for the message template editing, will the agent still be able to copy the message template for their mailings and change the language in the body of the email?

Version

18A