It's very straight forward, ability to delete messages in the "Sent" folder. I currently have 450+ pages of sent messages (a good chunk is automated notifications of purchases, or clan messages I send) and when loading this message box on devices it can lag terribly.

If I need to go back and review a conversation, it can be difficult to find or navigate the folder with the amount of information the page is trying to load each time.

Deleting the messages from the folder wouldn't delete the message in another user's inbox, just your copy. Even if there needed to be a waiting period before deleting a new message, it would still be more helpful than collecting messages I don't need all the way back to 2018.