Novell's white paper, "Novell GroupWise: Avoiding the Impact of Microsoft Exchange Server Security Issues," presents GroupWise as a more secure alternative to Exchange. The Microsoft white paper "Setting the Record Straight: A Response to Novell" refutes Novell's assertions about Exchange security.

http://www.novell.com/products/groupwise/documents.html

http://www.microsoft.com/exchange/evaluation/compare/novexchsec.asp