OK, so I've set this up in php.ini. Not sure if I have set it up right, though. This is what I have:
[mail function]
; For Win32 only.
; http://php.net/smtp
SMTP = smtp.office365.com
; http://php.net/smtp-port
smtp_port = 587
; For Win32 only.
; http://php.net/sendmail-from
sendmail_from = utfacilities@example.com
It still isn't working. Am I still missing something?
Another thing that I have noticed, is that in the Update Email Address page for this e-mail address, if Authentication Required is set to Yes, it fails when I click Save Changes. If I set this same e-mail address up on our old (LAMP) server, with Authentication Required set to Yes, it works just fine, and sends e-mail.