There's an option to turn this off and on (or on and off depending on your point of view) in your account settings. Maybe that's got itself in a twist?
To find out, click on your login name at top right corner of the forum page (between your avatar and the envelope symbol for conversations) to get the drop down menu to show, then from the drop down select 'Weekly Digest' (you should see it under 'ignoring' and above 'Ads manager') .
Check in there to see if you have a tick in the box next to 'Unsubscribe' if you do, tick subscribe, save that change, away you go!
However, if you show a tick next to 'subscribe', given that computers are involved (and you're also sure that for the first time in living memory it hasn't been consigned to spam by your email program), I would suggest that you unsubscribe yourself, save that change, then nip back to the same page and then subscribe again and save that change! May seem a bit ridiculous but the number of times I've been caught out by check boxes saying one thing and doing an other, is so numerous that I'd be a slightly richer man had I been paid a £1/$1 for them all!
Hopefully one or the other of my suggestions will kick the electrons into order and something approaching normality will return the next time these emails are sent out....fingers crossed
Apologies if any of this is not new to you or you've already been there and checked already...