disabling auto-save in private messaging

We are wondering how or if can we disable auto-save? Currently autosave happens on both forum posts and private messages. The issue with private messages is that whatever text has been written will be saved and so if a member switches conversations and replies to more than one person the text will appear in the message box of whichever conversation they open. This has the potential for members to accidentally send messages intended for one recipient to another recipient and therefore has implications for GDPR