Is it possible to create a server-side rule for my exchange 2003 organization that will create a folder in each mailbox and move particular messages to that folder? I would like to create a Voicemail folder and move messages based on the criteria to the Voicemail folder.

Theres no feature that can accomplish your task in the exchange 2003 natively per my knowledge Workaround: The Mailbox Manager tab in the Recipient Policy can achieve the task partially. We can use it to automatically process the contents of users' mailboxes, and enter all types of Message Class except the Message Class of Voice mail in the Exclude specific message classes field (So Mailbox Manager will only process Voice mail). Also, we set the action to Move the message to System Cleanup folders (So all Voice mails will enter to System Cleanup folders) Resources: How to use recipient policies to control mailboxes in Exchange 2000 and Exchange 2003 Taking a good look at Exchange 2003 Mailbox Manager Mailbox Management