Sure, you can go through the list and remove one entry at a time. Or you delete them all at once.
Remove All Blocked Senders at Once in Windows Mail
To delete all addresses from your list of blocked Windows Mail senders:
Go to your Windows Mail settings in the Windows registry.Make a backup copy of the list of blocked senders.Click on the Block Senders List key with the right mouse button.Select Delete from the menu.Click Yes to confirm the deletion.
Remove All Blocked Senders at Once in Outlook Express
To empty your list of blocked senders in one go in Outlook Express:
Go to your Outlook Express settings in the Windows registry. Make a backup copy of the list of blocked senders. Click on the Block Senders key with the right mouse button. Select Delete from the menu. Click Yes.
That’s it. Outlook Express should start with an empty list of blocked senders now. Note that this method of deleting blocked senders removes both the list of blocked email and the list of blocked news senders.