Email sending error - 550 Relay Not Permitted

This guide explains what causes the Email Sending Error 550 – Relay Not Permitted and why it prevents your emails from being sent. By using this guide, you’ll learn how to configure your email settings correctly so your messages are sent successfully.

Issue

Users may see the 550 Relay Not Permitted error or message when sending email. It can appear in several places: 

• Email clients like Microsoft Outlook, Mozilla Thunderbird, or Apple Mail when the message fails to send. 
• Webmail platforms such as Roundcube after clicking Send. 
• Mail server logs or bounce messages in hosting panels like cPanel & WHM or Plesk. 

Common error messages:

550 Relay Not Permitted

550 5.7.1 Relaying denied

550 5.7.1 Relay access denied

Cause

This error usually occurs when the email server cannot verify that the sender has permission to relay messages. Common causes include: 

• SMTP authentication is not enabled in the email client. 
• Incorrect SMTP server settings are configured. 
• Wrong username or password is used for authentication. 
• The “From” email address does not match the authenticated email account. 
• The email client is using Port 25, which is often restricted by internet service providers. 
• The sender is attempting to use an SMTP server that does not host the email account.
   

When any of these conditions occur, the mail server rejects the email and returns the 550 Relay Not Permitted error. 

Solution

To resolve the 550 Relay Not Permitted error, verify and update your outgoing mail server (SMTP) settings.

1. Make sure SMTP authentication is enabled in your email client. Look for an option such as “My outgoing server (SMTP) requires authentication” and enable it. Most email clients also allow you to select “Use same settings as incoming mail server.” 
2. Confirm that the correct SMTP server settings are being used. Typical settings include: 
   • SMTP Server: mail.(yourdomain.com) 
   • Port: 587 (TLS) or 465 (SSL) 
   • Authentication: Enabled 
   • Username: Full email address 
   • Password: Email account password 

It is also important to ensure that the email address used in the “From” field matches the authenticated email account, unless the mail server specifically allows aliases. 

If the issue persists, try sending the email through webmail. If the email sends successfully in webmail, the problem is likely related to the configuration of the email client.