Hi,
Microsoft are literally throwing Ooples emails away.
I have had a fair amount of experience with Office 365 and there are a couple of bits that help.
The first is to use this form to get MS to accept the IP and hopefully decrease the SCL.
https://support.microsoft.com/en-us/...37655404916638
The second is to ensure the account that is sending the emails is authenticated and not just relayed unauthenticated of the mail servers.
They are also starting to use DKIM a lot more too alongside the SPF record checks.