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Receiving a "554 Message not allowed - [320]" error

You may see the above error in a failed delivery message or as an SMTP error when sending emails to Yahoo Mail accounts. We've got some possible causes for the error, as well as suggestions for preventing it in the future.

"554 Message not allowed - [320]" 

  • Indicates that your email was not accepted because the message in question may contain characteristics that Yahoo Mail will not accept for policy reasons.
    - For example, it is against Yahoo Mail's policy to accept messages with malicious content or manipulated header information, such as:
    • A falsified origination point.
    • An altered sending date.
    • A forged email address.
  • If you're the administrator for the mail server in question, we ask that you review outgoing messages for potentially objectionable content or practices.
    - See our Best practices for bulk mail senders and postmasters for sending to Yahoo! Mail for additional information.

Note: Yahoo is unable to disclose specific information regarding our filtering practices.

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