Ask HN: Anyone succeed to delist your IP from ProofPoint blocklist

I run an email forwarding app and recently one of our outgoing mail servers are blocked by proofpoint, which is used by icloud.com or me.com. We still have another IP and I routed icloud email to that server but our icloud email volume are very low and I think their flagging is a false positive.

I attempted to delist use their office form on https://ipcheck.proofpoint.com but no response so far

Anyone know how to reach their team who have visibility to this process?

Much appreciate.