exJello is a JavaMail provider that connects to a Microsoft Exchange server using the WebDAV interface exposed by Outlook Web Access.

See also:

http://java.sun.com/products/javamail/Third_Party.html

http://code.google.com/p/java-libpst/ <- Read Outlooks PST file format from Java

http://sourceforge.net/projects/j-xchange/ <- Connect to Exchange via CD0 1.2.1 (not MAPI), see MAPI/CDO download for Exchange 2007>

http://poi.apache.org/ <- Project to access Microsoft-formatted documents, include rudimentary Outlook file support.