SMTP Authentication to be enabled on mail client
Getting the following undelivery message while sending emails
Delivery has failed to these recipients or groups:
[email protected] ([email protected]) A problem occurred during the delivery of this message to this e-mail address. Try sending this message again. If the problem continues, please contact your helpdesk.
The following organization rejected your message: contoso.com
Solution:
The message error 550 is normally due to SMTP Authentication not enabled on the mail client.
Versions Outlook 98 and later
- Select Services on the Outlook Tools menu, which opens the email Services window (If your Tools menu has Accounts instead of Services, use the Outlook Express instructions above)
- Highlight the Internet E-mail account, and click the Properties button to show the settings
- Click the Servers tab, which shows you all the mail server settings
- In the Outgoing Mail Server section, make sure the My server requires authentication checkbox is checked
- Click the Settings… button next to it and be sure the Use the same settings as my incoming mail server option is selected.
Follow below article for further clarification