I have a VPS with WHM/Cpanel that I host all of my clients' sites on. I use the standard WHM EXIM mail server. We've built the IP address reputation up to a 99 on senderscore.org and gotten us removed from all blacklists. However, I still get rejects from about 1 in 10 mail servers claiming we have a poor MTA reputation. Unfortunately, I don't think I can setup a proper RDNS record because the IP address belongs to my vps provider. Also, gmail keeps sending us to spam folder. Any advice, suggestions, experts that can help?