# DKIM verification failures - Microsoft 365 / Exchange Online **URL:** \ **Category:** Technical Help\ **Created:** [February 7, 2025, 2:37pm UTC](https://forum.dmarcian.com/t/dkim-verification-failures-microsoft-365-exchange-online/2679 "2025-02-07T14:37:43Z")\ **Posts on this page:** 17\ **Page:** 1
**Author:** ![Asher](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.dmarcian.com/asher/32/104_2.png) [@Asher](https://forum.dmarcian.com/u/Asher)\ **Post date:** [February 7, 2025, 2:37pm UTC](https://forum.dmarcian.com/t/dkim-verification-failures-microsoft-365-exchange-online/2679/1 "2025-02-07T14:37:43Z")
Hi everyone, There has been an issue happening for some time regarding Microsoft Exchange Online / 365 where DKIM verification reported as part of DMARC shows “temperror” or “fail” as a verdict. You may notice in your DMARC report that this issue only occurs with Microsoft, and that after verification you find nothing wrong with the DKIM public key record and your DNS. ![image](https://canada1.discourse-cdn.com/flex036/uploads/dmarcian/original/1X/94a577b0354f4ca7e885d6e6733227a3360b2df6.png) Review of email headers for those emails failing DKIM will reveal the following details in the Authentication-Results header: - dkim=fail (dns timeout) for temperror verdicts - dkim=fail (no key for signature) for the fail verdicts In this circumstance, this is highly likely due to a bug being investigated by Microsoft regarding the way it handles its DNS check to obtain the DKIM public key record. Microsoft is aware and are working on a fix with a deployment ETA of end of February. In my review of failures across dmarcian customers and their data, the failure rate due to this bug is about 0.25 to 0.5%. Email sources that are DMARC compliant strictly through DKIM only will be impacted by the “dkim=fail (no key for signature)” verdict. Meanwhile, the issue causing the temperror verdict, dkim=fail (dns timeout), will see the severity of policy applied reduced by 1 level: reject → quarantine and quarantine → no action. This is a behaviour I was able to confirm through testing with Exchange Online. The only mitigating steps is to have both DKIM and SPF alignment configured wherever possible. If this issue occurs, then SPF alignment will still allow a passing DMARC verdict, and prevent impact to legitimate mail flow due to the bug. However, some sources are not capable of SPF alignment, such as MailChimp. For information on whether or not a source is capable of SPF alignment, refer to our source database here: [DMARC.io](https://dmarc.io/source/index.html) If you are a dmarcian customer and you have further question or require support regarding this issue, contact us at [support@dmarcian.com](mailto:support@dmarcian.com). Otherwise, feel free to discuss your findings here. Thank you! ---
**Author:** ![CIGRK](https://avatars.discourse-cdn.com/v4/letter/c/aeb1de/32.png) [@CIGRK](https://forum.dmarcian.com/u/CIGRK)\ **Post date:** [March 6, 2025, 1:02pm UTC](https://forum.dmarcian.com/t/dkim-verification-failures-microsoft-365-exchange-online/2679/2 "2025-03-06T13:02:57Z")
Has anyone been able to find anything in service health in the M365 portal? I was hoping to track when this is fixed in there. ---
**Author:** ![Asher](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.dmarcian.com/asher/32/104_2.png) [@Asher](https://forum.dmarcian.com/u/Asher)\ **Post date:** [March 6, 2025, 1:27pm UTC](https://forum.dmarcian.com/t/dkim-verification-failures-microsoft-365-exchange-online/2679/3 "2025-03-06T13:27:44Z")
Hi CIGRK and welcome to the forums. This bug is not currently documented publicly by Microsoft, so there is nothing to find unfortunately. I met with them on Feb 28th and the issue is ongoing. The rollout has not yet completed, and no ETA was given. I will share what I learn as soon as they provide me another update. Meanwhile, I can confirm the issue is still ongoing through data analysis across our customer base. Let’s hope we hear back soon. ---
**Author:** ![Asher](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.dmarcian.com/asher/32/104_2.png) [@Asher](https://forum.dmarcian.com/u/Asher)\ **Post date:** [March 28, 2025, 6:30pm UTC](https://forum.dmarcian.com/t/dkim-verification-failures-microsoft-365-exchange-online/2679/4 "2025-03-28T18:30:21Z")
A review of data shows the issue is still ongoing as of March 27th. The frequency of “temperror” results are on the way down, but failures due to to “dkim=fail (no key for signature)” remain. I will provide an update once more information becomes available. ---
**Author:** ![tvisconti](https://avatars.discourse-cdn.com/v4/letter/t/ba8739/32.png) [@tvisconti](https://forum.dmarcian.com/u/tvisconti)\ **Post date:** [April 1, 2025, 4:09pm UTC](https://forum.dmarcian.com/t/dkim-verification-failures-microsoft-365-exchange-online/2679/5 "2025-04-01T16:09:26Z")
@Asher, would you be willing to request Microsoft convert this to a bug that is tracked and acknowledge publicly by their team. I think it would be to their benefit to limit additional unnecessary support requests and needless troubleshooting. ---
**Author:** ![Asher](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.dmarcian.com/asher/32/104_2.png) [@Asher](https://forum.dmarcian.com/u/Asher)\ **Post date:** [April 3, 2025, 1:16pm UTC](https://forum.dmarcian.com/t/dkim-verification-failures-microsoft-365-exchange-online/2679/6 "2025-04-03T13:16:09Z")
It was brought up already, but they have not acknowledged whether or not they intend to do that. ---
**Author:** ![CIGRK](https://avatars.discourse-cdn.com/v4/letter/c/aeb1de/32.png) [@CIGRK](https://forum.dmarcian.com/u/CIGRK)\ **Post date:** [May 12, 2025, 12:02pm UTC](https://forum.dmarcian.com/t/dkim-verification-failures-microsoft-365-exchange-online/2679/7 "2025-05-12T12:02:55Z")
I have attempted to open a ticket with Microsoft to push them to get this issue fixed or at least acknowledge it. So far, they’ve been saying it’s an issue with my spam filter. ---
**Author:** ![CIGRK](https://avatars.discourse-cdn.com/v4/letter/c/aeb1de/32.png) [@CIGRK](https://forum.dmarcian.com/u/CIGRK)\ **Post date:** [May 30, 2025, 1:41pm UTC](https://forum.dmarcian.com/t/dkim-verification-failures-microsoft-365-exchange-online/2679/8 "2025-05-30T13:41:46Z")
@Asher - Have you heard back from Microsoft at all? ---
**Author:** ![Asher](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.dmarcian.com/asher/32/104_2.png) [@Asher](https://forum.dmarcian.com/u/Asher)\ **Post date:** [May 30, 2025, 2:08pm UTC](https://forum.dmarcian.com/t/dkim-verification-failures-microsoft-365-exchange-online/2679/9 "2025-05-30T14:08:07Z")
Yes, but they have been vague regarding the issue at large, and they seem to be addressing this tenant by tenant. All I can recommend at this stage is for each individual customers to submit evidence of the issue as previously discussed. ---
**Author:** ![CIGRK](https://avatars.discourse-cdn.com/v4/letter/c/aeb1de/32.png) [@CIGRK](https://forum.dmarcian.com/u/CIGRK)\ **Post date:** [May 30, 2025, 3:58pm UTC](https://forum.dmarcian.com/t/dkim-verification-failures-microsoft-365-exchange-online/2679/10 "2025-05-30T15:58:04Z")
I’ve got a ticket open with them, but I’m not getting real far, especially now that I have SPF in alignment on most of our domains. Emails are sending, but would like to see them resolve this issue also. You wouldn’t have a case number with them or anything that I could point them in the right direction would you? ---
**Author:** ![Bram](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.dmarcian.com/bram/32/461_2.png) [@Bram](https://forum.dmarcian.com/u/Bram)\ **Post date:** [June 19, 2025, 2:47pm UTC](https://forum.dmarcian.com/t/dkim-verification-failures-microsoft-365-exchange-online/2679/11 "2025-06-19T14:47:33Z")
Unfortunately we’ve been also affected by this issue since early this week. A huge spike in bounces at several customers with the DKIM=fail issue. Has there been any news from MS on this ? At least a public statement or a trackable case ? ---
**Author:** ![Asher](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.dmarcian.com/asher/32/104_2.png) [@Asher](https://forum.dmarcian.com/u/Asher)\ **Post date:** [June 20, 2025, 1:33pm UTC](https://forum.dmarcian.com/t/dkim-verification-failures-microsoft-365-exchange-online/2679/12 "2025-06-20T13:33:57Z")
Hi Bram and welcome to the forum! There is no public statement or case number to track from Microsoft. My current communication with them across several tenant has consistently received the same advice: Open a case with them with the appropriate evidence you are experiencing the issue. My understanding is that they have a configuration they can apply to mitigate the problem per tenant, at this for the moment. ---
**Author:** ![rsetht](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.dmarcian.com/rsetht/32/462_2.png) [@rsetht](https://forum.dmarcian.com/u/rsetht)\ **Post date:** [June 26, 2025, 5:15pm UTC](https://forum.dmarcian.com/t/dkim-verification-failures-microsoft-365-exchange-online/2679/13 "2025-06-26T17:15:26Z")
We’re having a significant problem suddenly with alleged DKIM failures, but ONLY from [outlook.com](http://outlook.com) servers. Can anyone point me where to go to open a case with Microsoft? Thanks! ---
**Author:** ![Asher](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.dmarcian.com/asher/32/104_2.png) [@Asher](https://forum.dmarcian.com/u/Asher)\ **Post date:** [July 3, 2025, 8:13pm UTC](https://forum.dmarcian.com/t/dkim-verification-failures-microsoft-365-exchange-online/2679/14 "2025-07-03T20:13:35Z")
Hi rsetht and welcome to the forums! If you are a Microsoft customer, you can get more information here. > **[Get support - Microsoft 365 admin](https://learn.microsoft.com/en-us/microsoft-365/admin/get-help-support?view=o365-worldwide)** > > Learn how to get online or phone support for your Microsoft 365 for business subscription. You must be an admin for a business subscription to get support. If you are not, unfortunately there is no way to open a case directly with Microsoft. You would need to work with one of the recipient impacted by the issue to open a case. ---
**Author:** ![aaron](https://avatars.discourse-cdn.com/v4/letter/a/e19adc/32.png) [@aaron](https://forum.dmarcian.com/u/aaron)\ **Post date:** [July 8, 2025, 2:38pm UTC](https://forum.dmarcian.com/t/dkim-verification-failures-microsoft-365-exchange-online/2679/15 "2025-07-08T14:38:36Z")
We’ve opened a case with Microsoft and although it has been “escalated” to engineers, I’m curious if there’s examples of evidence that works. We sent screenshots of dmarcian and message headers illustrating the issue, but MS has been really quiet acknowledging the issue from our supplied evidence. Or key phrases to use with MS Support? I was informed they are not able to see this forum post because all external links are blocked from the support agent we received. ---
**Author:** ![CIGRK](https://avatars.discourse-cdn.com/v4/letter/c/aeb1de/32.png) [@CIGRK](https://forum.dmarcian.com/u/CIGRK)\ **Post date:** [July 11, 2025, 11:44am UTC](https://forum.dmarcian.com/t/dkim-verification-failures-microsoft-365-exchange-online/2679/16 "2025-07-11T11:44:18Z")
I have had a ticket open for a few months now. I had some good data to give them a few weeks ago (emails that we had sent ourselves with DKIM failures), but they claim the data is too old now and they weren’t able to get to it right away. I’m not giving up… yet. ---
**Author:** ![steven](https://avatars.discourse-cdn.com/v4/letter/s/94ad74/32.png) [@steven](https://forum.dmarcian.com/u/steven)\ **Post date:** [August 14, 2025, 5:08pm UTC](https://forum.dmarcian.com/t/dkim-verification-failures-microsoft-365-exchange-online/2679/17 "2025-08-14T17:08:50Z")
We’ve been seeing this issue since at least October 2024 and I couldn’t figure out what was happening. This is a pretty significant problem for us with the volume of email we’re sending…