Error when you import a folder with MBX proxy addresses

When you try to import a .csv file into an Exchange Server folder with proxy addresses for mailboxes with an .mbx file name extension, you receive the following error message Also, the following event is logged in the Application event log.

The import procedure does not work because you cannot use the same proxy address, of any type, for more than one recipient. In this case, the value of MBX:1 or MBX:0 is assigned to the first record in the .csv file and cannot be assigned to any subsequent entries in the .csv file.

The folder import procedure cannot be adopted to include or exclude mailboxes from cleaning. You can achieve this only by using the Microsoft Exchange Server Mailbox Manager tool.

When you use the Mailbox Manager tool, you can either include or set a policy for each container to exclude a mailbox. Corresponding to the selection, the tool generates a proxy address for the corresponding mailbox of either type MBX:0 or type MBX:1. However, if you try to import a .csv file, it does not work and you receive the error message that is mentioned in the "Symptoms" section.

You can use Mailbox Manager to select mailboxes that you want to exclude from automated message deletion. With MBClean, there was a limit to the number of mailboxes that could be excluded. This limitation was caused by the way that the mailbox exclusion information was being stored. To overcome this limitation, Mailbox Manager stores the exclusion information on the mailbox itself. Mailbox Manager uses a custom proxy address of type MBX and adds this proxy address to each mailbox that is excluded. For example, if you use Mailbox Manager to exclude a mailbox named "Test," a proxy address of type MBX is added to the Test mailbox. When Mailbox Manager processes the mailboxes for cleanup, it ignores the mailboxes that have the proxy address MBX.