If you want to access an MS Exchange server to read messages, notes, tasks, calenders, contacts, … there is a library which has been provided by Microsoft. It’s called EWS Java API1.1 and provides the package microsoft.exchange.webservices.data. However the Library is kind of abandoned but it does still work with Exchange 2010 SP1. Unfortunately it does have some old dependencies and makes some trouble if you try to compile it.
You can download the Jar here: EWS Java API1.1.5