I was told that this attribute affects communication between exch 03 and 2010. Is this correct, what is its function? How does it affect users? Thanks..

Hi 1. All versions of Outlook use the LegacyExchangeDN property when a user delegates access to folders by using the Outlook client. 2.Since Exchange 2000 the mailbox’s X.500 address has been stored in the legacyExchangeDN attribute in Active Directory. The legacyExchangeDN value is set when a mailbox is created, and includes the name of the Exchange administrative group where the mailbox belongs. LegacyExchangeDN values typically look like this: /o=Organisation/ou=Administrative Group/cn= Recipients/cn=Username For example when you move mailbox from Exchange 2003 to Exchange 2010 your user-defined admin groups are replaced by a single admin group named “Exchange Administrative Group” Then it uses the new admin group name in their legacyExchangeDN values. Any new e-mail sent from Outlook using the previously cached X.500 address was being rejected because the old X.500 address no longer existed in the organization. 3.Office Outlook 2003 and earlier versions use the LegacyExchangeDN property to get free/busy information.