Do you have access to a Microsoft-hosted Exchange account? Exchange support is now available in Thunderbird Daily for testing, and we could use your help making sure it's ready for all our users in a few months. See our post on the Developers' mailing list to learn how to help:
https://thunderbird.topicbox.com/groups/planning/T6c8bc7224f85aab6-M863a0ab83939d71bdf14361e