If you are reading about this topic, here are three nuances that are often overlooked:
Find the address you want to restore and click next to it. how do i unblock emails on gmail
When you unblock someone, Gmail does not automatically recover the emails they sent you while they were blocked. Those emails were likely auto-deleted or sent to Spam. If you are expecting an important document from them, you need to ask them to resend it. If you are reading about this topic, here