What Is Causing This Error?
This error typically occurs when the SMTP server configuration does not allow changes to the sender’s identity after the initial connection has been authenticated. It may happen if the email client attempts to modify the ‘From’ address or use a different identity within a single SMTP session.
Resolving the Error – Solution
To resolve this issue, ensure that any attempts to send emails adhere to the SMTP server’s policies regarding identity. This means avoiding changes to the ‘From’ address after authentication or setting up separate SMTP connections for each unique sender identity.
For WordPress users utilizing SMTP to send emails, plugins like Easy WP SMTP can help manage sender identities correctly, ensuring compliance with your SMTP server’s policies.
That’s it! Now you know how to fix the 503-5.7.0 error.
If you’d like to learn how to troubleshoot other common errors, check out the following tutorials: