[swinog] Mails from Proton to Outlook land in spam

Hi all,

I wonder if someone could point me in a correct direction for debugging mails between Proton and Outlook landing in spam... What happens is

* my domain XXX plugged to mail.protonmail.ch. * my 2nd domain YYY plugged to mail.protection.outlook.com. * every mail sent from Proton to Outlook lands in spam * headers as seen by Outlook indicate SCL score 5

The content I use for the test is not anything synthetic but a real message. In the headers I can also see that the "basic configuration" is correct, i.e.

* SPF passed * DKIM passed * DMARC passed

so this gives no useful information sadly. Maybe someone here has experience with debugging Microsoft? The issue is that this makes my private mailbox unusable as whoever out there uses Outlook as their mail service is not getting my emails. Quite sick...

Thanks a lot for any help, Mateusz