http://blogs.msdn.com/crm/archive/2009/06/23/how-to-toggle-smart-matching-in-microsoft-dynamics-crm-4-0.aspxSmart matching is the default and the only email correlation strategy shipped with CRM 4. Smart matching uses the subject of the current email along with the email recipients of the current email and generates subject hash and address recipient hash anden-USCommunityServer 2.1 SP1 (Build: 61025.2)