Your blocked list is like the junk drawer of your email account. You forget what is in there until something breaks. Set a calendar reminder to check your Filters and Blocked Addresses once a quarter.
Once you unblock, future emails will arrive normally. To be extra safe, you should also add that address to your or create a Filter that says "Never send it to Spam." gmail unblock email
Then it hits you: Did I accidentally block them last month? Your blocked list is like the junk drawer
The Great Gmail Escape: How to Find and Unblock an Email Address You Didn’t Mean to Block Once you unblock, future emails will arrive normally
You might be surprised to find that you accidentally blocked your boss, your child’s school, or the airline confirmation service six months ago.
Unlike Spam, which holds mail for 30 days, blocked emails go straight to the digital void. The sender doesn’t get a "Delivery failed" notification. Gmail just eats the message. They will never reach your Inbox again until you unblock them.