Error: "554 5.7.5 (AU01) Message not accepted for policy reasons" when sending to Yahoo

This error message indicates that your email wasn't accepted because it failed authentication checks against your sending domain's DomainKeys or DKIM policy.

Note: If you're not the system administrator for the mail servers affected, we encourage you to contact the administrator, so they can look into the situation further.

Why your email may be rejected by Yahoo

We only reject emails for failing DomainKeys or DKIM authentication when both of these conditions apply:

  1. The signing domain has given us explicit indication that all emails from the domain must be signed and authenticated with DomainKeys and/or DKIM to prevent forgery.
    - The signing domain is identified in the "d=" tag of the DomainKeys/DKIM signature.
  2. The rejected email couldn't be authenticated against the sending domain's policy, for example, due to a missing or bad signature).

Next steps: We recommend that you contact your domain's mail administrator and notify them of the problem.