99% of the time this is caused by a typo. As much as we'd love to say, "it's not you, it's us" - it generally ain't. Sorry, them's the facts - backed by data. To make sure your email address and phone number is correctly entered, go to your Account > Settings >Notifications.
It's also possible your email provider mistakenly marked our emails as spam and sent them to your spam or junk folders. You can help avoid this by removing our messages from your spam list and adding "firstname.lastname@example.org" as a contact. Then, call your ISP or email provider and let them how mean spirited it was to block us in the first place.