OK, thanks for the additional info.
In Outlook 2010, I have a Global Address List, and other sub-categories, but I'm guessing that Aqua Mail wants to look under the heading I have in there called Contacts (which is currently empty for me). I assume that's what you mean when you say Aqua Mail will sync my "personal address book from the Exchange server".
If I'm understanding this right, I'll likely just forget about Aqua Mail contact images and continue with the "lettered" icons instead. I don't feel the need to create/populate an Exchange Contacts folder with names I already have in my GAL.