Displaying sender photo from LDAP in Outlook reading pane

How do I make Outlook 2003 automatically show the picture of the sender
stored in LDAP?

I know I could save the sender to my contacts and attach a picture to that
contact, then it'll be shown in the reading pane. But that's not convenient
because I can't possibly anticipate everybody that may send me email, and
this is a manual process... What I need is to have the application
automatically do it even for people not in my contact, as long as their LDAP
entry have pictures associated.

Or, is there a way to invoke an add-in to display the sender picture in the
reading pane? Then I can make a program to grab the picture from wherever...

Thanks.
- alex