How to Determine Exchange Server Version and SP level

Open Exchange System Manager
click help
click about Exchange
Note Version
compare the version to the build number in the following list:

Version                                             Build number              Release date 
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Microsoft Exchange Server 4.0 4.0.837 April 1996
Microsoft Exchange Server 4.0 (a) 4.0.993 August 1996
Microsoft Exchange Server 4.0 SP1 4.0.838 May 1996
Microsoft Exchange Server 4.0 SP2 4.0.993 August 1996
Microsoft Exchange Server 4.0 SP3 4.0.994 November 1996
Microsoft Exchange Server 4.0 SP4 4.0.995 April 1997
Microsoft Exchange Server 4.0 SP5 4.0.996 May 1998

Microsoft Exchange Server 5.0 5.0.1457 March 1997
Microsoft Exchange Server 5.0 SP1 5.0.1458 June 1997
Microsoft Exchange Server 5.0 SP2 5.0.1460 February 1998

Microsoft Exchange Server 5.5 5.5.1960 November 1997
Microsoft Exchange Server 5.5 SP1 5.5.2232 July 1998
Microsoft Exchange Server 5.5 SP2 5.5.2448 December 1998
Microsoft Exchange Server 5.5 SP3 5.5.2650 September 1999
Microsoft Exchange Server 5.5 SP4 5.5.2653 November 2000

Microsoft Exchange 2000 Server 6.0.4417 October 2000
Microsoft Exchange 2000 Server (a) 6.0.4417 January 2001
Microsoft Exchange 2000 Server SP1 6.0.4712 July 2001
Microsoft Exchange 2000 Server SP2 6.0.5762 December 2001
Microsoft Exchange 2000 Server SP3 6.0.6249 August 2002
Microsoft Exchange 2000 Server post-SP3 6.0.6487 September 2003
Microsoft Exchange 2000 Server post-SP3 6.0.6556 April 2004
Microsoft Exchange 2000 Server post-SP3 6.0.6603 August 2004

Microsoft Exchange Server 2003 6.5.6944 October 2003
Microsoft Exchange Server 2003 SP1 6.5.7226 May 2004
Microsoft Exchange Server 2003 SP2 6.5.7638 October 2005

Microsoft Exchange Server 2007 8.0.685.24 or 8.0.685.25 December 2006
Microsoft Exchange Server 2007 SP1 8.1.0240.006 November 2007