XADM: Importing Blank Value Won't Modify Mailbox Value

When you import a comma delimited file into Microsoft Exchange Server by using the Microsoft Exchange Administrator program, and a blank value is included, the existing value on the General tab of the Mailbox properties page will not be replaced.

If there is a value on the General tab, the comma comma value (,,) import will not change the value to blank. The same will occur if a comma space comma is used (, ,). To replace a value on the General tab of the Mailbox properties page, the imported file must contain a comma double-quote space double-quote comma value (," ",).

For additional information on removing fields, please see the following article in the Microsoft Knowledge Base: