We are experiencing issues with email from our users being immediately rejected (during HELO) by certain mail providers (mostly earthlink).
We have Zimbra installed in a NE multi-server setup. Our two mta hostnames are mta1.ourdomain.com and mta2.ourdomain.com. Our public name is smtp.ourdomain.com.
Could the issue be the differences between our hostnames and our public ip? If so, is there a setting we should change in postfix so that it greets by smtp.ourdomain.com? Or are other mail providers even seeing mta1 and mta2?