SMTP authentication is required, Error Number: 0x800CCC79

SMTP authentication is required, Error Number: 0x800CCC79

Cause of the Issue

0x800CCC79 appears in Microsoft Outlook Express when you try to send e-mail. The outgoing SMTP server denies to accept the e-mail without authentication prior sending an e-mail. The sample of the error is pasted below which can vary.

Error Samples

The message could not be sent because one of the recipients was rejected by the server. The rejected e-mail address was ‘’. Subject ‘Re: Test’, Account: ‘’, Server: ‘’, Protocol: SMTP, Server Response: ‘530 SMTP authentication is required.’, Port: 25, Secure(SSL): No, Server Error: 530, Error Number: 0x800CCC79

Troubleshooting the Issue

For Outlook Express

  1. In Outlook Express go to “Tools” and then click on “Accounts…”
  2. Select the account for which you are getting error while sending mail from
  3. Click “Properties” button
  4. Click “Servers” tab
  5. Select “My server requires authentication” under “Outgoing Mail Server” section
  6. Click “Settings” button
  7. If your SMTP login credentials are same as the incoming server then choose “Use same settings as my incoming mail server” otherwise choose “Log on using” and provide SMTP server credential.
  8. Click “OK” again click “OK” and then click “Close”

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