In the outgoing emails we use in our domains SPF + DKIM without any problem.

But with the inbound emails some time ago we're receiving emails from some of our customers/suppliers signed with DKIM, but they don't have set any public signature on it's DNS Servers.

In that case our server answers a 5.5.0 error saying:

550-DKIM: encountered the following problem validating domain.com:
550 pubkey_unavailable

We found lots of customers/suppliers which are using Google hosted mail (Google Apps). Google servers sign the mails using DKIM but they don't set the DKIM signature on it's DNS servers.

IMHO it's a bad configuration on it's part because if you're signing the email I should check the signature. And if I don't find the domain signature I cannot check if the mail it's legal or not, so I return it to you.

This should be the correct behavior, or I should acccept these emails?

  • Nobody will be able to give you a definitive answer on that. It all depends heavily whether your business can work without receiving those E-Mails.
    – pacey
    Sep 28, 2016 at 12:14


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