http://msmvps.com/blogs/ehlo/archive/2007/10/13/1246421.aspxThe Microsoft Exchange Team has made a significant update to the Mailbox Server Role Storage Requirements Calculator - v 11.8 . BTW, I mentioned in a previous post that the spreadsheet didn't convert well to Excel 2003. Well, apparently they fixedenCommunityServer 2008.5 SP2 (Build: 40407.4157)