[perfecto_maduro]

consider yourself lucky you even got a response.

My IP is sparkling clean for many years now, dkim/spf etc, but gets blocked on any MS mail server. Tried appealing and heard nothing whatsoever.

[andix]

Is it possible that Microsoft distrusts your IP range? Some providers are known not to be very responsive to abuse reports. And then whole IP ranges get (soft) blacklisted, and individual IPs can’t be unblocked, without having a very strong case.