The migration tool that can be used for migration is called EShuttle and is made by a company called Stellar Technologies. It is a third party tool that we helped integrated with Scalix and is now partially supported. Stellar supports EShuttle, Notes, IMAP and Exchange as Legacy systems.
Please check the website,
http://www.inwaretechnologies.com/
you can download a trial version and try it out.
For more help contact Scalix sales.