I am getting the following info in the undeliverable response when trying to send email to a particular domain,
firstname.lastname@example.org on 06/06/2006 9:15 AM
There was a SMTP communication problem with the recipient's email server. Please contact your system administrator.
<myemailserver.my-domain.local #5.5.0 smtp;573 Validating Sender>
1. I suspect that the recipient server is doing a reverse lookup to validate our domain. Our ISP own's the static IP issued to us therefore I expect that they would have to make the reverse lookup entry in thier DNS. Is this correct?
2. I thought the the 573 error was a generic response meaning the server is not available. How does the text "Validating Sender" get in the response message?
3. I tried telnet rcptdomain.com 25
250 anothermailserver.com your name is not my-domain.com
Our name is my-domain.com but would not be available by reverse lookup as discussed above.
Are my assumptions correct? What is the fix?