If you have an email from the sender in your folder or inbox, you can unblock them quickly: Open the message from the sender.
Based on your search for an "interesting article" about this topic, you likely came across a guide explaining that unblocking in Gmail isn't always obvious because the setting is hidden inside the email conversation itself. how do i unblock emails on gmail
You can manage blocked contacts across all Google services, including Gmail, by following the steps on Google Help for iPhone & iPad . This involves navigating to your Google Account profile > People & sharing > Blocked . Troubleshooting Missing Emails If you have an email from the sender