POPcon - description from Softdepia.com:
POPcon connects your POP3 mailboxes to your MS Exchange Server?. POPcon download the emails from POP3 mailboxes and distributes them to exchange mailboxes according to the recipient information found in the mail headers. The software is compatible to Exchange Server 5.5 and Exchange 2000 Server versions on Windows NT 4.0 as well as Windows 2000 or XP. POPcon installs as a OS service and runs in the background with no user logged in. New: POPcon Pro checks each incomming email with its built-in RAV virusscanner. Emails that contain viruses are encapsulated in a warning message and can be diverted to the postmaster. Antivirus signatures are automatically updated weekly or daily.
POPcon is a "Free to try" program. You can download and try it for an evaluation period.