Forum Discussion
Authentication-Results-Original email header
emails from my tenant have started getting the below Authentication-Results-Original: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=domain.com; as well as ...
Authentication-Results-Original are from previous mail server. Authentication-Results are results of last receiving servers' email auth checks.
You can paste email header into dmarctester.com and find the status of SPF,DKIM and DMARC.
MXToolBox Message Analyzer has a known issue where it usually fails DKIM.