SMTP Authentication Errors

Problem

You see the following error while attempting to send email:

Could Not Authenticate

Cause

This error can occur for the following reasons:

  • The mail server is rejecting the SMTP details that you entered for Mail Provider in the Mail tab at Configuration () > System Settings > General Settings.
  • Password hashing is enabled on your Plesk server.

Solution

Make certain that all of the details in your Mail Provider configuration are correct in the Mail tab at Configuration () > System Settings > General Settings.

If the error persists and you use a Plesk server:

  1. Go to Tools & Settings > Security Policy and find the Storing email passwords section.
  2. Select Symmetric encryption for Storage method.
  3. Click OK.
For more information, see Plesk’s Enabling Mail Password Hashing documentation.
troubleshooting troubleshooting-article smtp-mail-provider

Last modified: 2026 June 3