iPhone users can see entire Public folder hierarchy on Exchange 2003

Interesting one this, and sounds odd initially but upon some further reading is an issue that is known around the iPhone.

http://discussions.apple.com/thread.jspa?messageID=6689175

It seems over IMAP the iPhone (perhaps through iTunes?) pulls down the entire PF hierarchy.

The workaround to this is that you can uncheck the option to "Include all public folders when a folder list is requested” on the IMAP virtual server under protocols in ESM.