Another exchange based post for calculating the bandwidth requirement for the exchange clients. Link follows: Donload the excel file: http://gallery.technet.microsoft.com/exchange/Exchange-Client-Network-8af1bf00/file/49302/4/Exchange%20Client%20Network%20Bandwidth%20Calculator%20-%20Public.0.48BETA4%20-%20TimeZone.v5.xlsx This is an excel file bearing 288KB of data.