: You do not need to install SP1 or SP2 beforehand; SP3 includes every public and security update released through September 2011.
: It fixed an issue where documents with custom security filters wouldn't show up in search alerts correctly. 2007-sp3
For IT administrators, Exchange Server 2007 SP3 (released earlier in 2010) was equally vital. : You do not need to install SP1
: A critical fix was implemented for crashes occurring when Microsoft Excel 2007 tried to open books saved in newer versions that used unsupported features. : A critical fix was implemented for crashes
: Improved handling of specialized calendars (like the Chinese New Year in Singapore) and fixed Unicode character display in error messages.
: Strengthened the Office Compatibility Pack for users working across different Office versions. Critical Beyond the Desktop: Exchange Server 2007 SP3