Microsoft recently updated its offline help files (Exch2013OnPremHelp.chm and Exch2013HybridHelp.chm) and placed them on the Microsoft download site: http://www.microsoft.com/en-us/download/details.aspx?id=35395

When you download these files and open them you don’t see anything, except the navigation structure:

By default Windows blocks these kinds of downloads for security reasons. You can unblock the .chm file by requesting the properties of the .chm file and unblock button.

Now when you open the .chm file you’ll see the contents as expected:

The .chm files are not always updated. The previous one was based on Exchange 2013 CU1. If you want to use the latest and most updated information regarding Exchange 2013 Microsoft recommends building your own book of TechNet articles as outlined in the following article: http://bit.ly/BuildTechnetBook (but I have to admit the .chm files work much better than an offline PDF file)