open the mail client then click on the Tools menu.
Scroll down to Message Rules and a flyout window opens - select Blocked Senders List.
Now all you need to do is locate the sender you do not want on the list and remove the email account from the list by selecting the account and then the remove button.
I have outlook express 6.I think i inadvertently removed a sender from sending me emails by clicking 'block sender' in the drop box under messages.How do I undo that so I can receive emails from that sender? I clicked on 'block sender' because i thought i would see something that would give me the option of blocking it or not.All it did was give me a message saying the sender has been blocked.I don't see anyway to allow that sender to be able to send again.Its important that I allow that sender to email me.Thank you