I am having a problem with our Exchange 2007 SP1 email server getting outbound email rejected by a few external companies' email servers. The reason they are being rejected is because our PTR record does not match the domain name our mail server presents in the HELO .
Our internal DNS domain is different from our public DNS domain. We use mycompany.local for our internal DNS space and mycompany.com for our public DNS space.
Our PTR record with our ISP points to mycompany.com.
The hostname of our mail server is hostname.mycompany.local.
It was by design that we separated public and private DNS spaces. With more companies combating spam by validating PTR records, I'm not sure what options I have to remedy this problem so email sent from us gets through to email servers that do reverse DNS checking.
If I configure the PTR record for mycompany.local this is technically wrong because mycompany.local cannot be resolved publicly.
I can't change the hostname of the Exchange server but if there is a way to change the name Exchange presents in the HELO greeting, I am afraid it will cause issues for my end users who use Outlook.
Does anyone have a suggestion to resolve this problem so email from our system will be delivered to email servers that do reverse DNS checking? Thanks in advance.