If a client is using outlooks express so you can’t ghost. Here is the address on Microsoft site on how to backup express e-mail.
Preserving Blocked Senders List and/or Other Mail Rules
The procedure to preserve the blocked senders list and other mail rules is detailed in the following Microsoft Knowledge Base article:
276511 (http://support.microsoft.com/kb/276511/) How to backup and restore Outlook Express Blocked Senders list and other mail rules