For a limited time, O’Reilly and Microsoft Press have the “early access” editions of Exchange 2013 Inside Out: Connectivity, Clients, and Unified Messaging and Exchange 2013 Inside Out: Mailbox and High Availability on sale for $19.99 each. This is a fantastic deal given that you get early electronic access to the books– I am still in the midst of working on my book, but you can get access to parts of it now to learn what you need to know, well in advance of its official on-sale date. The deal is good until 0500 PDT on July 3, so you have a bit of time to take advantage of it. (Note that the sale doesn’t apply to the bundle that includes both the print book and the early access electronic edition).