1. With the Outlook open, go to Junk Email folder.

2. Right click on the email you want to unblock and then select Junk>Never Block Sender.

3. If you don’t see the email you want to unblock, click on Junk E-mail Options.

4. Click on Blocked Senders. Highlight the Sender and then Remove.

5. Click OK to save the settings.
Please view this step by step video: