We have a self-hosted mail server at our business's single, static IP address (mail.companyA.com). Our website is hosted by another company at a different IP address (companyA.com). Our emails use the @companyA.com domain.
Sometimes we send emails to certain clients that get through fine, and sometimes we get bouncebacks from the same client indicating we are blocked. Short-story: I am concerned that a reverse DNS lookup done by some companies with stricter requirements on emails is getting us in trouble depending on the rDNS lookup result that appears first.
MXToolbox reports that a rDNS lookup on our static IP address (from which we sent our emails) has two PTR records: One to mail.companyA.com and the other to companyA.com
Should I request our ISP to remove the PTR record to companyA.com, leaving only mail.companyA.com - or will this create problems?