Well I agree that the issue you are originally referring to in the post is pretty much going to have to be a front end fix, but the transfer messages could be an account level setting couldn't they? Like submit a pull request to make all messages encrypted and require active key sign in or perhaps have the ability as an account setting that can be manually disabled on a per account basis? I'm not trying to hijack the topic, I just think they are similar issues in the sense that they both relate to undesirable messages being received.

edit I guess it could cause further complications with exchanges though... maybe that wouldn't be such a simple fix.