I am forever searching around for Visio stencils for Exchange so I thought I would post a list on my blog, so I and anyone else who needs them can find the links in one spot.  The Exchange 2013 stencils have objects that represent elements of Exchange 2010 and 2007 just in case you only wanted to download one :)

 

Office Viso Stencil for Exchange 2013 and Office 365

 Microsoft Exchange 2010 Visio Stencil

 Microsoft Exchange 2007 Visio Stencil