Mailing List Archive

[Bug 2947] New: dkim=fail (signature did not verify) delivery to Microsoft Exchange
https://bugs.exim.org/show_bug.cgi?id=2947

Bug ID: 2947
Summary: dkim=fail (signature did not verify) delivery to
Microsoft Exchange
Product: Exim
Version: 4.95
Hardware: All
OS: All
Status: NEW
Severity: wishlist
Priority: medium
Component: DKIM
Assignee: tom@duncanthrax.net
Reporter: drandre222@gmail.com
CC: exim-dev@exim.org

After searching the bug forums here, I could not discover any relevant or
similar issues. Since this appears to be originating from Exim email, I am
opening a specific case on the DKIM failures.

Using cPanel and the Exim servers to send fullly authenticated emails (DMARC,
DKIM, and SPF), we are receiving DKIM error from receiving emails from emails
sent from Exim servers to Microsoft servers. Sending emails to Gmail, Yahoo,
AOL, iCloud, and other third parties the emails arrive with standard pass
headers.

Below are the header results from the email from Exim to O365 Exchange:
> Authentication-Results: spf=pass (sender IP is xx.xx.xx.xx)
> smtp.mailfrom=usservicecenter.net; dkim=fail (signature did not verify)
> header.d=usservicecenter.net;dmarc=pass action=none
> header.from=usservicecenter.net;compauth=pass reason=100

Here are the header results from the email from Exim to Gmail:
> ARC-Authentication-Results: i=1; mx.google.com; dkim=pass
> header.i=@usservicecenter.net header.s=default header.b=NZsAFDFG;
> spf=pass (google.com: domain of andre@usservicecenter.net designates
> xx.xx.xx.xx as permitted sender) smtp.mailfrom=andre@usservicecenter.net;
> dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=usservicecenter.net


Our service provider states this is a known issue and there are no solutions.
The DNS records are correctly set.

The records have been validated even through online checkers such as:
(1) https://dkimvalidator.com/
(2) https://dmarcly.com/tools/ (emailing check@dmarcly.com)


They are currently using exim (4.95-6.cp11104) and exim-26.

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