SPF problem on valid domain name

[Charles-André Bélanger]

Hello,

We are starting to have problems (Received-SPF fail) since a few days on some email, here a example from a valid email that was cut by O365 and put in the quarantine.

This email was generated by us via Adobe electronic signature and the error is:

Received-SPF: Fail (protection.outlook.com: domain of mail.na4.adobesign.com

does not designate 104.47.75.169 as permitted sender)

after digging a bit, I realise that this IP is an IP from Microsoft, it's a bit strange that O365 is blocking an email from one of it's own IP address ?

I'm not sure where to start to investigate this problem

any advise will be helpfull

thanks

[#2]

Try adding the adobe service as trusted ARC sender: https://learn.microsoft.com/en-us/microsoft-365/security/office-365-security/use-arc-exceptions-to-m...