Quote Originally Posted by Jeeqbit View Post
You can take a screenshot of the names so that you remember, though. [...]
Visit their world, Player Search them, then right-click and Add to Blacklist.
[...] You can also go to the lodestone and search for them there and block them.
Fair options around, these two were new to me so thanks for the tips! I'll note that it requires the subject of the deny / mute to be online when you're using Player Search, but at least that overcomes the hurdle that you'd need to see their messages in log.
Also, not everyone has their characters visible on The Loadstone, but that's a decent fallback which should work for a sufficient number of people. (Tested via an alt of a friend).

Additionally neither of these methods work for the Mute list, but it is what it is I suppose.