RATS Dyna block list is common to avoid Trojan and bots sending mail to recipients. SPAMRATS detect unhealthy and invalid rDNS records entries in server. Remove Blacklist from span filter domain, add PTR record in DNS server. In case of on-perm outgoing mail apparently get the IP from ISP.
In my scenario, mail service has hosted in O365 and multiple web application pointing to same IP. Due to this RATS Dyna marked as blacklist http://www.spamrats.com/bl?[xx.xx.xx.xx]. Whereas domain purchased in GoDaddy.com service provider. rDNS supposed to be added in service provider end refer https://in.godaddy.com/help/add-my-own-host-names-as-nameservers-12320 where we could archive and fix an issues.
Adding ‘Host name’ under advanced feature to fix rDNS issues. Here added ‘mail.sathiya.io’ to 10.xx.xx.xx; Make sure to validate an entry with mxtoolbox.com or dnschecker.org