Microsoft Message delivery
If the emails are landing in the SPAM folder check the message delivery in View Message Source.
The emails will land in SPAM if the message delivery ends with these values 0xO1NDTD02, 0yO1NDTD02, 0zO1NDTD02
0xO1NDTD02 - If the Content is spam.
0yO1NDTD02 - If the IP/Domain reputation is bad.
0zO1NDTD02 - If the IP/Domain reputation is bad.
The emails will land in INBOX if the message delivery ends with these values 0xO1NDTD0z, 0yO1NDTD0z, 0zO1NDTD0z
Also check for SCL, BCL and PCL values
The SCL value must be less than 3, if it is more than 3 emails will land in SPAM
SCL value: 1 - 3 (Inbox)
4 - 5 (IP Spam)
7 (Content Spam)
Above 7 (Domain Spam)
The BCL value must be less than 5, if it is more than 5 emails will land in SPAM
BCL value: 1 - 5 (Inbox)
Above 5 (Domain spam)
The PCL value must be less than 3, if it is more than 3 emails will land in SPAM
PCL value: 1 - 3 (Inbox)
Above 3 (Phishing content)