Stopped receiving email notifications from Youtube. (And Don’t Know Why?)

I recently stopped getting email notifications from the channels I subscribed to on Youtube. I've checked all my subscriptions on Youtube, to make sure that I do have the box checked to receive email notifications when a video is posted. No changes have been made there. Everything has been working fine, since the change from Hotmail to Outlook, but for the last few weeks, I haven't been getting any emails from Youtube.