If by mistake you have blocked someone and you no longer receive emails from that person you can unblock the person at any time.
The following are the steps for unblocking Email addresses in AOL:
Step 1: The first step to unblock a sender is to go to AOL Keyword: Mail controls.
Step 2: The next step is in the blocked mail from the addresses I specify the text box, remove the email address which you want to receive emails from.
Step 3: After removing the email addresses Click Save.
Step 4: The last step is to close the Spam Settings window.