Migrate to Netherlands or UK. Check the IPs first if they are listed, (Spamhaus, Proofpoint and Talos intelegence or use MultiRBL.valli.org - Blacklist, Whitelist and FCrDNS check tool) if yes release and renew the IPs and only when you are sure you are on a good IP, go ahead and reserve it and then make a ptr record. I know it is a tidious job but you should have reserved you IP in the first place. Warm up the IP. Good luck