Quick question regarding how email works

Hello,

Im currenly using 4 cPanel servers (server.domain.com, server.domain2.com, server.domain3.com server.domain4.com) to load balance an email application that send mails to a lot of my customers (autoresponder plus) and im not sure how should i configure the rDNS on each server.
Im currently sending emails from support@domain.com. What i did is i transferred the same cPanel account (domain.com) to the rest of all the servers included mailbox support@domain.com so when the program logins to each of the 4 smtp servers previously mentioned the software sends the emails from the user support@domain.com.
My question is, should i need to setup the rDNS on every main server IP to the same record? I mean setup the rDNS to point domain.com. Or should i setup the rDNS to point each server domain? Ex. setup main server ip of server.domain2.com rDNS to domain2.com and NOT domain.com.

I hope i have been clear and you guys could understand this situation.

Thank you for wasting the time to read this post. I will really appreciate any suggestion you can advice.

Thank you in advance!

Cheers.

 

Can someone shred me some light on this please.

Thank you.

 

Thank you for clarifying me this out.

Regards.