If you've noticed you're no longer receiving emails from a specific contact in your Yahoo Mail account, there’s a good chance you may have accidentally blocked them. Blocking is a useful feature to stop spam or unwanted messages, but it can also catch legitimate senders by mistake.
If you still have an old email from the blocked sender in your Spam or Trash folder: yahoo unblock email
Unblocking an address doesn't automatically retrieve emails that were blocked or deleted in the past. Here’s what to check next: If you've noticed you're no longer receiving emails
Manage spam and mailing lists in New Yahoo Mail | Yahoo Help yahoo unblock email