If mailboxes on Exchange 2000 Server contain over 4 gigabytes (GBs) of data, Exchange System Manager may show the total size of the mailbox as 0 instead of the true mailbox size.
This problem can occur if Exchange System Manager reads the wrong property tag for mailboxes that are larger than 4 GB.
To resolve this problem, obtain the latest service pack for Microsoft Exchange 2000 Server. For additional information, click the following article number to view the article in the
Microsoft Knowledge Base:
XGEN: How to Obtain the Latest Exchange 2000 Server Service Pack
Microsoft has confirmed that this is a problem in Microsoft Exchange 2000 Server.
This problem was first corrected in Microsoft Exchange 2000 Server Service Pack 2.