Hi Ken
Not sure if this is your issue but. this also happened to my twice by accident. at the bottom of ever email it says
If you do not have access to the account, you can click this link to directly block emails like this to be sent to your email address, or Unblock.
as I was swiping left to delete a lot of emails, I must have selected Block, it does not need an verification. find an old email and select the" unblock" email option and it fixed my issue. or email support to unblock you email address. as a test you can change or add a new email address in the notification section for a tag, and see if it gets through.