Reverse DNS Issues Causing Problems With Email

Hello
I'm using a hosting service (rackforce.com) which provides a whm/cpanel access to my servers. I'm having trouble with users not being able to connect to their email. It's seem intermittant. I also have set up my gmail account to go to the server and get mail and it is erroring out.

I'm basically a web designer who has been given the duties of administrating my own servers. Everything has run pretty smooth up to now, but now I have some unhappy customers.

The server that I speak of is at 209.97.208.60

Do you offer "git me out of trouble services"

I'm working with my host company but we're not there yet and was trying to get more eyes on the issue.

Thanks
Greg Mann
Newark OH