Because Gmail uses a filter system rather than a traditional "block list," unblocking is simply a matter of removing a rule.
If you still have a message from the person (check your folder if it’s missing from your Inbox), this is the fastest way to unblock them. Open Gmail on your computer or mobile app. Open an email from the blocked sender. how do i unblock a contact on gmail
If you followed the steps above and the person's emails are still missing, ask them to send a fresh test email. Gmail learns from your behavior; it may take 24 hours for the algorithm to fully trust that sender again. Because Gmail uses a filter system rather than
That’s it. You are now unblocked.