@joeyh @erebion @clacke @leyrer
MS also uses UCEPROTECT as an RBL. UCEPROTECT is a blackmail scam. It lists every Linode & DigitalOcean IP as a spammer, regardless of whether *your* IP has ever sent spam, & offers to de-list you (regardless of behavior) for 89 CHF (about $100).
No reputable email service should use UCEPROTECT but MS does & won't explain why.
https://blog.sucuri.net/2021/02/uceprotect-when-rbls-go-bad.html#uceprotect-scam