If that's the case, it wouldn't work unless you put your e-mail address in, but I'm not going to pretend that's anything other than unfounded speculation.

While I'm wildly speculating, it might also be updates for the yourwebapps service that the people checking the box are being told about, or possible changes to an individual Board, or early warnings that the Internet is under attack by a malevolent force. Google seems oddly tight-dataed on the matter, which may mean that either the yourwebapps daily update function is rarely used, or unimportant... or sinister.