Back in May at the InboxExpo conference in Atlanta, I was told by a consultant to very large senders that they advise customers to set their DMARC to "p=quarantine" because they had been observing that Microsoft's processing of some emails was causing DKIM failures - in as much as 30% of their customers' email campaigns traffic.
We didn't discuss the technical details (other than Microsoft's processing altered the emails in such a way as to cause the DKIM fails), but thought that might be helpful to share (possibly related?) as regards the OP's issue with Mimecast, with whom we had numerous difficulties, and whose Partnership we elected not to renew a while back. Regards, Mark -- _________________________________________________________________ L. Mark Stone, Founder North America's Leading Zimbra VAR/BSP/Training Partner For Companies With Mission-Critical Email Needs ----- Original Message ----- | From: "Alessandro Vesely via mailop" <mailop@mailop.org> | To: "mailop" <mailop@mailop.org> | Sent: Thursday, October 17, 2024 1:00:09 PM | Subject: Re: [mailop] SPF fragility vs. utility | On Wed 16/Oct/2024 18:00:47 +0200 Dave Crocker via mailop wrote: |> [...] |> |> 7. The myth that SPF is simple to implement is because it is simple for a |> sender to create a basic SPF record. It does not mean that it is simple to |> create a more elaborate record, or to ensure that all authorized sending sites |> are list. Nor does it mean that it is simple for a receiver to provide |> fully-conformant processing. | | | DKIM is much more difficult. Heritage header adjustments are still encysted in | a number of MTAs, intermittently causing mysterious DKIM failures. | | |> Please consider: If SPF were deprecated, was would be the actual, significant |> effects on email anti-abuse processes? | | | Missing a backup authentication method would make DMARC even less reliable. | | | Best | Ale | -- | | | | | _______________________________________________ | mailop mailing list | mailop@mailop.org | https://list.mailop.org/listinfo/mailop _______________________________________________ mailop mailing list mailop@mailop.org https://list.mailop.org/listinfo/mailop
