My email server is permanently flagged as spam in SNDS. No way to unblock it. I've tried everything. Its not sending any marketing or automated emails.
Microsoft just wants you to use O365 and happily blocks a lot of smaller email senders. Not even gmail is that strict. They've only greylisted my server for a few months and then unblocked it fully.
Same experience here. I did everything right and could send email from my VPS to basically any other provider, except Microsoft. I had to give up and use the SMTP proxy provided by my VPS vendor to not have all my emails to @outlook.com or @hotmail.com end up in spam.