You might want to include some actual information with your post such as
Outlook version, information store, where the user is typing initials and
what you imagined should happen when they did. Neither autoresolution nor
autocompletion uses initials. To what could you possibly be referring when
you are expecting a "name to pop up?"

I apologize, when adding to the TO: section while composing a new message in
Outlook 2003, our users can typically type in an username (we are a small
company and usernames are intials, Ex. Leigh I. Blackburn LIB.) Usually the
username will resolve to the email address, however, some usernames are
mispelled, or simply wrong. an example is below, where Dennis A. Muchow,
"DAM" will only resolve when you type in DMA as opposed to DAM. I have
checked mailboxes, contact lists, and user properties and I cannot find where
it is getting these name from. Any further Ideas would be appreciated.