What do the numbers in SMTP error codes mean?

Discussion in 'Mail Server Support' started by popowich, Oct 24, 2010.

  1. popowich

    popowich EQ Forum Admin Staff Member

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    SMTP error codes are generally broken down into two categories of messages.

    The first is 4xx smtp error codes. Any error code in the 400's is a temporary error. You can infer from this that your outgoing mail server will continue to try and send the email in the hopes that it can be delivered at a later time.

    The second is 5xx smtp error codes. Error codes in the 500's are permanent errors. When a 5xx error is encountered your outgoing mail server should immediately stop trying to send the email and send you a bounce message, usually from mailer-daemon, letting you know that the email could not be delivered.

    Both categories of error codes should also provide a specific reason for why the error occurred allowing you to troubleshoot the problem and take the appropriate action going forward.
     


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