Non HostName mails are going to SPAM

Hi! I'm a CWPro user,
I'm having these issues and hopefully perhaps someone has gone through a similar situation can give a link / steps on a solution.

Host : KANS.CO.ID
Client-Domain : BRIB.CO.ID

problems :

• I would like to send email from BRIB.CO.ID through it's own mail.brib.co.id insead of piggybacking fro KANS
• Since the IP for KANS traces back to kans, It seems that email sent from BRIB when reversed dns by Google, traces back to kans.co.id (although i have kans & brib website on the same IP), it is being sent to SPAM. How does one solve this issue? Is it possible to map another IP I have, and use that network address when sending through BRIB, and then I can map the web also to his secondary IP and prevent rDNS issue caused by the first IP matching KANS, or do anyone has another solution?

TLDR; I need each client domain, to point to their own Mail Server, and able to be accepted by GMAIL without being sent to Spam because shared Ip address. If I need to get seperate IP's for each domain, it's ok. Any CWP / CentOS 7 alternative solution is welcomed. Thank you!