Thank you in advance for any helpful information!
A few things to check out:
Outlook web client - Microsoft abuses it though if not hosted on-prem and it has a few major bugs if you don't use the default settings.
Evolution-ews is a version of the evolution email client that will work with exchange.
DavMail Gateway might be worth a look http://davmail.sourceforge.net/index.html
Owl for Exchange - a plugin for thunderbird that is supposed to be os independent.
You might also use alternativeto.net for more suggestions.