dkim=fail (body hash did not verify) ONLY mails to outlook.com

Question

Hi, I configured my DNS-entries for SPF, DKIM and DMARC-authentications. Everything works fine, getting PASS on every mail from every provider (e.g. Gmail, T-online, Yahoo, random ISP mail-providers) EXCEPT outlook.com. Why is that? The error is: "dkim=fail (body hash did not verify)"
The error only happens most of the times, not always - only mails my webshop sends out (sending directly from Gmail smtp) have this issue. Is it the content of the body in the automatic mails? It does not seem like my DNS-entries are the issue here.

Thanks in advance

Answer 1

I found the issue. Outlook servers can not handle 8bit encoding when it comes to DKIM. I had to set the "Content-Transfer-Encoding"-Header to "quoted-printable" in my mail-script (phpmailer in this case):

$phpmailer->Encoding = 'quoted-printable';

Answer 2

Hallo,

I think I solved the issue. I deleted all of the body of the mails my webshop sends out and replaced it with just "Hello". Now the DKIM check passes which means your servers don't like something about the body in my previous mails. Could you let me know why this is an issue with Microsoft and not with other mail-recipient-servers? Why is the mail-body even an issue for DKIM-authentification?

Answer 3

Hi Seb Jo1,

Thanks for getting back.

We are glad to know that you were able to find the issue on your email account. Thank you for sharing this information, this would be very helpful to other community members reading here who has the same problem like yours. Hope everything is working fine now.

If you have any other questions, please feel free to post your concerns in the Office community, we are happy to provide you with instructions and answer all your queries.

Sincerely,

ReynaldoB

M365 Consumer Forum Moderator

Microsoft Community

Answer 4

Hi Seb Jo1,

Greetings!

Thank you for posting in Microsoft Community. We are happy to help.

I understand that you have concern about sending emails to Outlook.com domains wherein you are getting an error message. There are number of possible reasons why you are getting this type of error message. Let’s work together in finding the best solution to this issue.

To further assist you, I would receommend that you check on this article here for troubleshooting steps. This support article provides troubleshooting information for senders who are having trouble reaching Outlook.com users by email.

Please click on this link here. Troubleshooting (outlook.com)

Sincerely,

ReynaldoB

M365 Consumer Forum Moderator

Microsoft Community