451 Requested action aborted Reject due to policy restrictions.

Reason

Due to unusually high email traffic and lack of aligned DKIM signing of your emails, acceptance of your emails was deferred.

Solution

Therefore, make sure that your messages have a valid DKIM signature, which matches your From domain(RFC 5322.From) to achieve a DKIM alignment, at least in relaxed form.

Below you will find examples that illustrate this requirement:

  • Example 1 (relaxed DKIM alignment)
    • DKIM Domain: example.com
    • From Domain(RFC 5322.From): child.example.com

  • Example 2 (relaxed DKIM alignment)
    • DKIM Domain: child.example.com
    • From Domain(RFC 5322.From): example.com

  • Example 3 (strict DKIM alignment)
    • DKIM Domain: example.com
    • From Domain(RFC 5322.From): example.com

  • Example 4 (strict DKIM alignment)
    • DKIM Domain: child.example.com
    • From Domain(RFC 5322.From): child.example.com

If this does not help you, you or the person responsible for managing your system can contact us using the following form.

If possible, please provide us with all helpful information for processing, such as

  • complete error message
  • DKIM domain you use to sign your emails
  • IP addresses, IP ranges (CIDR), AS