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"550 Authentication is Required for Relay" when Sending Email

Problem:

Emails sent from an email client, like Microsoft Outlook or Outlook Express, result in a "550 Authentication is required for relay" error and are not delivered. 


Solution:

A "550 Authentication is required for relay" error indicates that your email server requires SMTP authentication in order to send outgoing mail, but the email client used to send email has not been authenticated with your username and password. Fortunately, resolving this error can be done quickly and easily. You simply need to configure your email client to send the appropriate credentials. In most email clients, SMTP authentication can be enabled by editing the account configuration and adjusting the Outgoing Server / SMTP settings.
 
That said, the exact steps for enabling SMTP authentication will vary depending on the email client being used. We've provided steps below for a few email clients. If the application you use is not listed, or for further instruction, please review your email client's support documentation. 
 
SMTP Authentication in Microsoft Outlook 2010 for Windows
 
  1. Click on File then hover over Info and click on Account Settings
  2. Select your email address from the list of accounts and click Change
  3. Click on More Settings.... Then click on the Outgoing Server tab.
  4. Check the box next to My outgoing server (SMTP) requires authentication and ensure the Use same settings as my incoming mail server is selected. 
  5. Click OK. Then click Next.
  6. Click Finish to complete the configuration. 
 
SMTP Authentication in Microsoft Outlook 2003
 
  1. Click on the Tools menu and select Email Accounts.
  2. Select View or change existing e-mail accounts and click Next.
  3. Select your email address from the list of accounts and click Change
  4. Click on More Settings. Then click on the Outgoing Server tab.
  5. Check the box next to My outgoing server (SMTP) requires authentication and ensure the Use same settings as my incoming mail server is selected. 
  6. Click OK. Then click Next.
  7. Click Finish to complete the configuration.
 
SMTP Authentication in Microsoft Outlook Express
 
  1. Click on the Tools menu and select Accounts.
  2. Select the Mail tab.
  3. Select your email address from the list of accounts and click on Properties. Then click on the Servers tab. 
  4. Under Outgoing Mail Server, check the box next to My server requires authentication.
  5. Click on the Settings button and ensure Use same setting as my incoming mail server is selected.
  6. Click OK. Then Apply the changes. 
  7. Click OK then Close to complete the configuration.
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