But that’s not the IP where your e-mail originates from; Cloudflare is not an outgoing e-mail provider, only INCOMING web proxy.
The IP that sends the e-mail, and the one that the remote mail server sees, is not the IP of your domain-over-the-web, rather than the IP which originated the connection - YOUR mail server, as @cs-cf wrote above - 173.203.187.118. This is the IP that should be removed from the blacklist, and is probably on their owners (Rackspace) to handle this.
OR… many people just go to “e-mail as a service” and pay someone to handle this getting-more-difficult-every-day task instead of them. For example, services like Amazon SES or SendGrid (easier)…