NAV 2016, Office 365, Email Notifications using Purchase Workflow Approvals

I am implementing NAV 2016 on Azure with Office 365 and I am getting the below error when I am using Email Notifications using Purchase Workflow Approvals.

“The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.7.57 SMTP; Client was not authenticated to send anonymous mail during MAIL FROM”

Can someone help please