When you send using Office 365 SMTP servers, you may receive error messages.
"Cannot send the message. Verify the e-mail address in your account properties. The server responded: 530 5.7.57 SMTP; Client was not authenticated to send anonymous mail during MAIL FROM [*.PROD.OUTLOOK.COM]"
If you receive this error message when you are adding the account to a POP or IMAP client, you need to confirm the settings in More Settings, Outgoing Server tab. Tick the option to use the incoming username and password for sending mail.
This may be trying to use Direct Send.
When you use Direct Send, you can send mail without authenticating. This is useful for printers, scanners, other devices, and applications but is not recommended for Outlook or other email client. When you use Outlook, you should use auto account setup and set the account up as a Microsoft Exchange account. If you need to set up a SMTP account in Outlook, you can find the correct the POP/IMAP and SMTP settings to use in Outlook on the web's Settings.
See these articles for more information and instructions for setting up the SMTP client.