I've been getting them for the past week, and didn't change anything. Probably there was some kind of wikidot-wide change. I'll see if I can get things back the way they were.
EDIT: Yes, it's a new feature called "Watching" which appears to be wikidot-wide, mandatory for anyone who edits a page or responds to a thread. Stupidly, it's designed to be opt-out. There should be a link at the bottom of the e-mail so you can opt-out of this stuff.
Apparently it's for people who have 30-40 wiki's to keep track of… but since we only have the one, and we're always hitting Recent Posts or Recent Changes, I really don't see the utility.