Ask HN: How to get reputable email IP?

We got assigned to the shared IP pool (SendGrid), where most of the IPs are blacklisted by Outlook. Most of the times emails are not even reaching spam (bounce, because of bad IP reputation).

We need to solve this problem ASAP: we can't onboard new customers if they don't receive our emails. Going to dedicated IP would require couple of weeks of warmup (and I'm doing it in background).

Is there a provider that would provide us with reputable shared IP with high sending volume?