How to Troubleshoot Missing Values for ExtensionAttribute Attributes
Microsoft Exchange Server 2007 will reach end of support on April 11, 2017. To stay supported, you will need to upgrade. For more information, see Resources to help you upgrade your Office 2007 servers and clients.
Topic Last Modified: 2008-01-30
This topic provides information about how to troubleshoot when all existing values for the attribute named extensionAttribute X (where X is a value from 1 through 15) are cleared from the user account.
Microsoft Exchange Server 2007 clears all Exchange attributes from a user account before mailbox enabling that account to maintain consistent data. Because the extensionAttribute attributes are legacy Exchange attributes, these are cleared.
This behavior is by design. To work around this issue, you must save the extensionAttribute attributes information before mail enabling the accounts, and then apply the extensionAttribute attributes information after mailbox enabling.