An easy-access setting to turn off all dms. (customizable filter)

It's occurred to me that a lot of users think you can message anyone as long as you have their username and tag.  With the right privacy settings, as I'm sure you all know, you can completely block anyone accept your friends from messaging you.  I think it would be beneficial to add a easy-access and quick way to turn off all dms completely.  This will not only make it much more convenient to filter out who you want to dm and who you don't want to dm, but this also ensures that no one will dm you, which I'm sure will save a lot of time over on the support team answering these questions.  I think it would also be nice to add a little filter to go with it.  Maybe some examples are friends, server members, friends of friends, and no one.  A small idea, but I think would be huge for both the community, and the support team.