Most of the times you will get this error while configuring and sending emails via outlook. The main reson for this error is outlook is not authenticating your email account with server. You can follow below steps to resolve this error.
- Click on Outlook and navigate to Tools >> Account Settings
- Now click on particular email account and you will get email settings page.
- Here you have to enter all your details about your email account like email account, password, outgoing mail server etc.
- Now you will find “Outgoing server” tab, click on it.
- Now select checkbox option “My Outgoing (SMTP) server requires authentication” and click on “Next“ button.
- You will get a new message “Account successfully updated”, at last click on “Done” button.