@emoreno double check your logs and Default MTA setting. When I disabled authentication, it seemed to accept the settings (even though my server requires authentication), but in fact it was logging and error and defaulting the use PHP mail function. What ended up working for me is the following:
1) Update* osTicket's mail class at /include/pear/Net/SMTP.php changing line 176: $this->socket_options =$socket_options; to $this->socket_options = array('ssl' => array('verify_peer_name' => false));
2) Add the required emails to Cpanel with the same password as in Office365.
3) Use http://www.mail-tester.com/ to test for errors (which led me to fix the following deliverability issues)
A) Edit the domain SPF record
B) Add a dmarc TXT record to the domain
Replies by my Agents in the UI go to junk. I'm hoping the SPF record hasn't been updated yet and when it does it will solve the problem.