help to reenable program that I accidentally blocked

From: clearly (clearly_at_discussions.microsoft.com)
Date: 02/20/05 

Date: Sun, 20 Feb 2005 12:51:03 -0800

I installed SP2 and am using the security features that pops up and tells you
a program is trying to access your computer, and the default is to block
access.

However, I accidentally blocked a program from Outlook Express and need to
unblock it.

What can I do to unblock my mistake?