When you create an email in Outlook and you can connect and get incoming mail but the outgoing SMTP throws a 550 error and won’t send for you, the most common solution is to imply clik the box "My outgoing server (SMTP) requires authentication".
To get here access the Account Properties for the email. Depending on your version of Outlook, this could be Tools Accounts or Home Accounts. Once you enter into the account to edit or change it you need to go to the Outgoing Server tab.
Here you will see the check box.
If that doesn’t work please check the following settings.
Hopefully this solves your problem.