550 Relay not permitted

You will see the ‘550 - Relay not permitted’ error when you try to send an email from an email client, which does not have outgoing email authentication enabled. This is a default setting in most mail clients like Outlook Express or Mozilla Thunderbird. To quickly fix ‘550 - Relay not permitted’ and start sending out emails successfully, you will need to enable outgoing authentication.

Here is how you can enable authentication in some of the most commonly used e-mail clients:

• How to fix ‘550 Relay not permitted’ in Outlook Express on Windows
• How to fix ‘550 Relay not permitted’ in Outlook Express on OS X
• How to fix ‘550 Relay not permitted’ in Mozilla Thunderbird on Windows
• How to fix ‘550 Relay not permitted’ in other email clients

How to fix ‘550 Relay not permitted’ in Outlook Express on Windows:

1. Launch Outlook Express.
2. Under "Tools" select "Accounts..."
3. Select your account name and click "Properties" to edit your account.
4. Click the "Servers" tab.
5. Check the "My Server Requires Authentication" check box and the adjacent "settings" button.
6. Make sure that the "Use same settings as my Incoming Mail Server" radio button is selected.
7. Click the "OK" button twice, and the "close" button. You are finished.

How to fix ‘550 Relay not permitted’ in Outlook Express on OS X:

1. Launch Outlook Express.
2. Under "Tools" select "Accounts..."
3. Select your account name and click "Edit" to edit your account.
4. Under the "Sending Mail" section, click on the "Click here for advanced sending options" field.
5. Check the "SMTP Server Requires Authentication" check box.
6. Make sure that the "Use same settings as Incoming Mail Server" radio button is selected.
7. Close window. Click "OK". Close window. You are finished.

How to fix ‘550 Relay not permitted’ in Mozilla Thunderbird on Windows:

1. Launch your mail client.
2. Under 'Tools' select 'Account Settings'.
3. Scroll down your accounts and select 'Outgoing Server (SMTP)'.
4. Select your outgoing server and click 'Edit'.
5. Enable the 'Use name and password' option.
6. As username, type your full mailbox name, for example: myemail@my-best-domain.com
7. As password, type the respective password for this mailbox.
8. Click 'OK'.

How to fix ‘550 Relay not permitted’ in other email clients:

1. Launch your mail client.
2. Find the email account preferences window.
3. Find the settings for the SMTP (aka Outgoing) mail server.
4. Check the checkbox which asks if the SMTP mail server requires authentication (if necessary).
5. Enter the same "user name" (your email address) and password as your incoming (POP) mail server's, or click the "use same settings as Incoming Mail Server" radio button.
6. Save the changes and close your preferences windows. You are finished.