When preparing an Exchange 5.5 organization to be synchronized with the AD using the AD ADC, one important step is to check if you have multiple mailboxes with the same primary Windows NT account. Unlike Exchange 5.5, a mailbox is now an attribute of an object in the AD, not an object itself. Each user in the AD can only be matched to one mailbox. Therefore, for every mailbox that exists in the Information Store, a matching object must exist in the AD. The ADC defaults to creating disabled users in the AD if it cannot match a mailbox to a user. A custom attribute can be set on the mailbox to force the ADC to create a new object instead of matching to an existing user. This custom attribute is "NTDSNoMatch", by setting this attribute on resource type mailboxes, this allows the ADC to properly match the mailbox that does not have "NTDSNoMatch" set to the user account. NtdsAtrib can be used to help perform this task. It checks for mailboxes with a duplicate primary NT account, and determines if the mailboxes is the primary mailbox or a resource mailbox. It the creates a CSV file that can be imported into the Exchange 5.5 directory to automatically set Custom Attribute 10 to "NTDSNoMatch" for the resource mailboxes. ex2ksp3\server\support\utils\i386\ntdsatrb\setup.exe NtdsAtrib can be installed on any Windows 2000 computer. It does not need to be installed on the Exchange 5.5 server. The default installation is \program files\ntdsatrib\. NtdsAtrib must be run from a Windows 2000 machine, not Windows 9x or NT4. When running, you must also ensure the account you are using has permissions to read the Exchange 5.5 directory. Usage: ntdsatrib exchsrvname ntdsatrib exchsrvname:portnumber The Win2k machine must either be in the same domain as the 5.5 server or you must use the runas command: runas /user:exchdomain\administrator ntdsatrib exchsrvname The output of NtdsAtrib is a series of CSV files. A CSV file is created per site which can be directly imported into Exchange 5.5 Administrator. Each CSV file is named based on the site name. A general ntdsnomatch.csv file is created for custom configurations. This file cannot be directly imported into Ex5.5 and requires manual editing. All CSV files will have an entry for every mailbox that has a duplicate primary NT account. All CSV files are saved to the same directory as the NtdsAtrib utilility. The CSV files generated contain the following fields: Obj-Class Extension-Attribute-10 Display Name Primary Windows NT Account Alias Name Directory Name Home-Server Obj-Container If the ADC has already replicated and created disabled accounts in the AD, the the NtdsAtrib util can still be used to determine which mailboxes have duplicate NT accounts, but additional cleanup work will need to be done to ensure all mailboxes are matched properly.