I'm in the planning phase for a product that is based around an Exchange 2010 (SP2) server, where our items will be stored in public folders. There could be hundreds of thousands of items, and I want to know if Exchange has known issues - either hard limits or performance bottlenecks - with managing large number of items in a single folder, and whether we should architect our solution to split the items logically into several folders.
The last versions of Exchange I was heavily into were 5.5 and 2000, and I remember that any folder with over a couple of hundred items would start behaving badly, but that was a long while ago, and I couldn't find anything on TechNet other than Item Size limits.
Bonus question: at some point in the future the system might be migrated to Exchange 2013. Are there any changes there (other than the ability to have an arbitrary number of PF databases, if I understand correctly).