I had a customer ask about IMAP4 access to public folders when they were designing their 2010 transition plans because there is some ambiguity out there. If you dig around on the internet you may see a few links (and blogs) that has conflicting information:
Understanding Public Folders
Discontinued Features and De-Emphasized Functionality
Understanding POP3 and IMAP4
The first article titled Understanding Public Folders states that “In Exchange 2010, the following client applications can access public folders: Outlook 2010 ,Outlook 2007, Outlook 2003, Client applications compatible with IMAP4, such as Outlook Express”.
The second article called Discontinued Features and De-Emphasized Functionality mentions that “If you need this functionality, retain an Exchange 2003 server in your Exchange 2010 organization“.
And while the third article mentioned above, Understanding POP3 and IMAP4 says “IMAP4 also supports public folder access.” A bit confusing to say the least!
So what is true? Overall, the truth is that we don’t have public folder access via IMAP4 and haven’t had it since Exchange 2003. We removed PF access through IMAP4 with the release of Exchange 2007 which is mentioned in Terry Myerson’s blog about E12 back in 2006. http://msexchangeteam.com/archive/2006/02/20/419994.aspx