I am currently using the Thunderbird add-on ExQuilla for Microsoft Exchange to sync my work mails. However, the 60 days trial is about to expire and I am not willing to pay for it.
It must be able to sync mail with an Exchange server: receiving, sending, deleting, stay up to date after modifications with remote folders etc.
A nice plus would be calendar and contacts syncing as well, but I currently use Lightning and EWS provider plugins which are working correctly.
My first choice is a Thunderbird add-on.
I am also open to install some syncing service.
My last option would be to go with Evolution since it involves installing nearly 300 MB of stuff with my current setup.
It must be gratis for all kinds of usage, but it is not required to be free software.