This is weird, because although I unticked everything (my e-mail is cluttered as is), I still get e-mail notifications about a reply in a watched thread, but only occasionally and only for some threads. There's no rhyme or reason to it, sometimes it's twice a day and sometimes it's after several weeks. Also the threads it picks are absolutely random, like recently I got an e-mail for the 1M replies thread (OK, sounds reasonable) and just today for the Judas Priest thread - which I probably haven't written in in several years, probably. For many other threads I'm particularly active in, nothing.
And to make it even weirder, sometimes it ends up in the inbox and sometimes it ends up in spam. Again, I have no idea what the rule of thumb is there.