# Why would Mimecast alone report missing DKIM? **URL:** \ **Category:** Technical Help\ **Created:** [March 1, 2024, 6:45pm UTC](https://forum.dmarcian.com/t/why-would-mimecast-alone-report-missing-dkim/2421 "2024-03-01T18:45:17Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Fax\_Machines\_FTW](https://avatars.discourse-cdn.com/v4/letter/f/77aa72/32.png) [@Fax\_Machines\_FTW](https://forum.dmarcian.com/u/Fax_Machines_FTW)\ **Post date:** [March 1, 2024, 6:45pm UTC](https://forum.dmarcian.com/t/why-would-mimecast-alone-report-missing-dkim/2421/1 "2024-03-01T18:45:17Z")
Google, Yahoo and IronPort DMARC reports all report SFP and DKIM alignment, Mimecast reports DKIM isn’t present at all. I tried to use Mimecast’s DKIM lookup tool: [Mimecast DKIM Check | Mimecast](https://www.mimecast.com/products/dmarc-analyzer/dkim-check/) But it only generates what appears to be an unrelated error message of: “Error: An exception occured” MXToolbox (and dmarcian obviously) and every other tool I tried reports our DKIM record is valid. The absolute only thing that comes to mind is that our mail vendor set the selector name as “default” rather than “selector#” five years ago or more. I don’t know if that matters but it is the only straw within reach. There are a number of posts online going back many years reporting that Mimecast has issues with DKIM but none of the posts I could find explain how the issue was resolved. We don’t have any open lines of communication with the admin of the recipient and a previous email issue went unacknowledged when a point of contact there tried to escalate it. ---
**Author:** ![Fax\_Machines\_FTW](https://avatars.discourse-cdn.com/v4/letter/f/77aa72/32.png) [@Fax\_Machines\_FTW](https://forum.dmarcian.com/u/Fax_Machines_FTW)\ **Post date:** [March 6, 2024, 7:51pm UTC](https://forum.dmarcian.com/t/why-would-mimecast-alone-report-missing-dkim/2421/2 "2024-03-06T19:51:36Z")
This seems to be an issue internal to Mimecast. It is only [no-reply@ca-1.mimecastreport.com](mailto:no-reply@ca-1.mimecastreport.com) and [no-reply@us-1.mimecastreport.com](mailto:no-reply@us-1.mimecastreport.com) that are reporting DKIM to be missing. (ca-1 presumably referring to Canada) [no-reply@uk-1.mimecastreport.com](mailto:no-reply@uk-1.mimecastreport.com) reports full alignment. I have a feeling intermittent issues with DMARC are going to drive me nuts. ---
**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 8, 2024, 2:38pm UTC](https://forum.dmarcian.com/t/why-would-mimecast-alone-report-missing-dkim/2421/3 "2024-03-08T14:38:54Z")
Hi Fax\_Machines\_FTW and welcome to the forums. There could be a few reasons why this is happening, and of course without seeing your seeing first hand I can only make some educated guesses. The most common reason in my experience is the outbound signing in _ **Gateway | Policies** _ → _ **DNS Authentication - Outbound** _ policy having the DKIM signing scope set settings called “Addresses Based On” set to return address only, which will cause messages that have a null MAIL FROM to not be signed. I would start there. Ensure your signing policy uses “both” as a setting for the “Addresses Based On” drop down. I hope it helps! ---
**Author:** ![Fax\_Machines\_FTW](https://avatars.discourse-cdn.com/v4/letter/f/77aa72/32.png) [@Fax\_Machines\_FTW](https://forum.dmarcian.com/u/Fax_Machines_FTW)\ **Post date:** [March 21, 2024, 4:43pm UTC](https://forum.dmarcian.com/t/why-would-mimecast-alone-report-missing-dkim/2421/4 "2024-03-21T16:43:35Z")
Thanks for the suggestion. Having changed nothing yet the failure reports have stopped coming from Mimecast. Beginning on March 18th reports from [no-reply@us-1.mimecastreport.com](mailto:no-reply@us-1.mimecastreport.com) report DKIM alignment. We haven’t received one from the Canadian reporting address recently. Shrug.