You're failing GMail DKIM as "No valid DKIM" in Authentication-Results header

k234525 shared this problem ago

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Apparently in an attempt to address this https://userforum-en.mailbox.org/topic/2301-inconsistent-authentication-results-of-mailbox-servers-seems-potentially-risky you're now failing GMail/Google Mail via an "No Valid DKIM" line in Authentication-Results despite DKIM being present. Furthermore, there is no dkim=... entry at all in the Authentication-Results header anymore, only a dmarc=... entry. For a missing DKIM there should be dkim=none or similar. This seems like quite a mess. Also, it says "incoming_mbo" instead of a proper "something.mailbox.org" server name clients can trust.

I hope this can be fixed timely, it makes filtering malicious e-mail almost impossible based on this header.

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Replies (3)

k234525 ●

It would be nice if this didn't take weeks to fix. Do you have a beta program where such issues can be reported early?

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Peter ●

Is this still happening?

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k234525 ●

Sadly yes, I now forwarded an e-mail example to support@mailbox.org that is affected. Hopefully it will shed some light on what the problem is. Before the recent changes, the verification worked fine, so this is some new behavior of the mailbox servers that is suddenly causing trouble. Other senders than gmail also work fine.

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k234525 ●

DKIM has been broken for a month now...

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5422682 ●

But just yesterday they won an award for security with a DKIM criterion!

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k234525 ●

It's still not working properly. Some forwarded e-mails in particular will fail when they shouldn't (and I don't mean the kind where the signed headers were modified), the dkim= header part is randomly missing, and there is no proper identifying hostname in the Authentication-Results header.

It used to work fine, but then they changed something in July 2025 ish.

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mailbox.org Support ●

Hi,

thank you very much for your feedback. You are right, we are still experiencing some issues with DKIM. We are very sorry, and we are working on a solution, but we still have to ask for a little more patience. We will of course keep you updated and write here as soon as we have fixed the issue.

With kind regards
Your mailbox.org team

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k234525 ●

Thank you for the acknowledgment. Until now I wasn't quite sure if it was recognized as a problem.

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