I'm not 100% certain that I know what you are asking, but based on the way I interpret your question: There is no supported mechanism for doing this, because there is no supported mechanism for assigning a custom mAPIID. From an overview perspective, you would create a new attribute with a mAPIID known to never collide with anything that MSFT will ever use, then change the details templates for your OAB and Outlook for your languages. From: exchangelist-bounce@xxxxxxxxxxxxx [mailto:exchangelist-bounce@xxxxxxxxxxxxx] On Behalf Of Amit Kapoor Sent: Thursday, March 19, 2009 12:43 PM To: 'exchangelist@xxxxxxxxxxxxx' Subject: [ExchangeList] Changes MSExchange 2007 Attributes. Importance: High Hi, We have exchange 2007 service pack1. We have migrated this from Exchange 5.5. Exchange 5.5 has attribute called Assistant which is displayed in Address book. But now we want to change this attribute to the department number attribute which is available in Active directory. Assistant attribute is not visible in active directory. Is there is any we can change attribute Assistant with attribute of Active directory and made it visible in Exchange as well. Department number attribute has value in AD, but it is not visible in Exchange Address book. How can we make this attribute show value in Exchange and visible and replace the attribute Assistant. Any help on this will be appreciated. Regards, Amit Kapoor _____ DISCLAIMER: This e-mail and any attachments to it may contain confidential and proprietary material and is solely for the use of the intended recipient. Any review, use, disclosure, distribution or copying of this transmittal is prohibited except by or on behalf of the intended recipient. If you have received this transmittal in error, please notify the sender and destroy this e-mail and any attachments and all copies, whether electronic or printed.