As you might know, Outlook stores its mails and other stuff in a single PST file. There's a relatively new Java library called java-libpst for reading Outlook PST files. It is licensed under the LGPL and available over here: http://code.google.com/p/java-libpst/
I have tested the library on Outlook 2000 and Outlook 2003, with good results. It would be great if the library could be integrated into Tika.
Tran Nam Quang