This blog post title should be “back to the future”.
The reason for it is in the notes of the “emails delivery” chapter:
Notes: in the last week of August Office 365 had a strange behavior:
only the messages signed with dkim (signing domain aligned with the From address)
and dmarc record set (with any policy), were delivered to the Inbox
One of our main customers last week wrote me telling that
“all of our emails sent to Office 365 are being delivered to the Junk folder”.
I made a lot of tests and found out that the only way to fix it
was to have the DKIM signing domain aligned and activate DMARC (with any policy).
The delivery issue was fixed, so I decided to let it know to the world
and later to contact the other customers to make the required changes to their dns settings.
During the tests for the writing of the article, I’ve found that everything was back as before,
when a message passes the SPF check, it is usually delivered to the Inbox,
see: “email delivery test results”.
I’ll go back to check that all the RealSender customers have their TXT record
set correctly at least to pass the SPF email authentication.