Outlook server fail DMARC

Senior Member

Hello Community ! 

I started to implement SPF/DKIM/DMARC on my domain for the past week, and noted something strange on my reports : a small percentage of my mails fail DMARC for SPF


As you can see on the screenshot above, we can see that the header "MailFrom" is filled with an Outlook server, which is the reason why my DMARC is not aligned ( as my domain is not outlook.com )

However, something bother me : why does Outlook servers does not change this header for my domain name ? As is it only for 10% of my mails, I suppose that for 90% of them, it changes the header, right ?

Thank you for your help !

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