If you can't email to one person the machine is not the problem, the mail server makes the decision once it receives the email, not the printer.
If that user is on another domain, it is likely that you are setup without a relay server side so you can only email from the MFP to your internal domain.
As for the SSL/TLS issue, just don't bother with it, MS has done things right with their system and created virtual servers for their users so authentication is not even required.
Smtp server: [domain].mail.eo.outlook.com
Outgoing port: 25
No encryption, no authentication.
Example:
So if Xerox.com was your domain xerox-com.mail.eo.outlook.com
would be the SMTP server (That hyphen is not a misprint, you replace . with -)