How can they force you to not use Thunderbird mail? If I use Thunderbird mail to send an email to an Exchange user, would it be blocked? How about vice versa?
Well sure you can use Thunderbird but our IT department makes it harder. You need to authenticate more often if you use anything other than outlook and Thunderbird unfortunately doesn’t support office 365 calendar. Now the exchange server dropped support EWS forcing everyone to use their Graph API which is yet to be supported by Apple mail.