That's a pain in the butt! But I don't get them for threads. It's like several "friendly" reminders that I haven't added a coop or how to raise baby chicks.Go back to the beginning of your watch threads list...
Some may be still checked to watch and receive emails.
I get random emails from old watched threads every now and then and when I go to that thread to click unwatch..then re click to watch I make sure the "no emails" box is checked.
It's only from very old watched threads...for me.