To backup and restore Windows Mail messages, make a copy of all the files in the directory that contains the message and database files. The location of the message store can be found via Tools | Options | Advanced | Maintenance | Store Folder (the default is %USERPROFILE%\AppData\Local\Microsoft\Windows Mail\) and the location is also specified as the "Store Root" value under the Windows Mail registry key below.
In addition to backing up those files, export these 3 registry keys:
This is the most important registry key and contains nearly all the settings and rules for Windows Mail.
This key is kept for legacy purposes, but no longer contains much information. The Identities feature of Outlook Express has been removed in Windows Mail.
This key contains some information on the default accounts. In Outlook Express this key held all of the account information. In Windows Mail, most of the account information is now in .oeaccount files in the message store. See New Handling of Account Data on the Microsoft website. Note that when restoring a backed up copy, if Windows Vista has been reinstalled, the account passwords will need to be re-entered by the user manually.
Windows Mail now uses the Vista system wide Contacts instead of the address book. See Windows Contacts on the Microsoft website.
To restore a backed up copy of Windows Mail. Create a new directory that matches the previous directory and make sure it also matches the "Store Root" value listed under the Windows Mail registry key, and empty that directory of all files and subdirectories. Then copy the backed up files to that directory, making sure that the files are not read only. Run Regedit and delete the 3 registry keys listed above in the target partition, and then merge the backed up registry keys. Windows Mail can then be started and should be restored to the backed up state.
A similar method can be used to share the message store between bootable Vista partitions. The "Store Root" value in the registry can be equated so that the message store can be shared. Account passwords however will need to be entered manually between booting to each partition, unless one backs up and overwrites the .oeaccount files between each boot, due to the handling of the password information. When booting between partitions sharing the same message store, be mindful that many changes in settings are stored under the Windows Mail registry key, so changing such in one partition may not be reflected in the other OS partition unless the key is re-equated between each OS.