Salut,
je suis en galère… si une âme charitable passe par la 
https://forum.indie.host/t/status-around-spam-issues/3336
Merci!
tu as mis des relais mx en frontal ?
Je ne peux que partager ta peine, j’ai observé la même chose lors de tests récemment. J’ai posté un avis sur Trustpilot 
Repeatedly marks perfectly legitimate emails (talking SPF / DKIM / DMARC in order for the techies, with even DANE working), no matter how often you move them into your inbox.
Whitelisting a domain? Yeah, they have a form for it, but it doesn’t work either.
If all email services behaved as bad, email communication would be a nightmare!
En tout cas, tu n’es pas seul !
https://github.com/MicrosoftDocs/OfficeDocs-o365seccomp/issues/211
https://techcommunity.microsoft.com/t5/Exchange/Emails-to-Outlook-delivered-to-Junk-Email-folder-with-SCL-1/m-p/149871
https://github.com/MicrosoftDocs/OfficeDocs-o365seccomp/issues/442
le dernier lien contient quand même:
Hello everyone. I have a final answer regarding this article, and I’d like to apologize for any confusion before we set out. Parts of the header information are exposed for customers to read in documents like this one, but parts are never going to be exposed and are not destined or meant for documentation. One analogy for this is that asking after certain of the codes would be like as asking after the contents of encrypted text in headers. The codes that are available are published as guidance at this time. Other codes will not be published and there are no plans to publish them.
mind-blowing 
En bonus, trouvé sur Reddit:
It’s worse than you think. There has been a serious issue with junk mail filtering for months now and it’s only getting worse. A Google search will show all kinds of complaints recently. Apparently, Microsoft’s Anti-spam service is now the first thing to process email, meaning any custom rules to send mail to Inbox instead of Junk Email are completely bypassed. I’ve been getting dozens of spam messages sent to my Junk Email folder whereas in the past it was being sent to another folder per a custom rule. Any message that I forward from a Zoho mailbox goes directly to Outlook’s Junk Email folder regardless of custom rules or passing SPF/DKIM/DMARC/ARC (how many effing auth systems do we need, geez?). I’ve had open tickets with both Microsoft and Zoho for months going back and forth about this. Microsoft refuses to accept blame while they are clearly tweaking and mucking up their junk filtering processes.
The header to look for is X-Microsoft-Antispam-Mailbox-Delivery and the value RF:JunkEmail is what sends the message straight to Junk Email.
ils ont leur régles ?
écrivons les notres.
… nous chatons !
Je ne comprends pas cette reponse.
Merci pour ton soutient, je vais eplucher tout cela!