On 11 Jun 2015, at 00:20, Timothy Murphy <gayle...@eircom.net> wrote:
> Here helen.gayleard.com is the internal name of my server > (on which postfix and dovecot are running), > while mail.eircom.net is my smarthost. helen.gayleard.com does not resolve in the public DNS and mail.eircom.net is correctly saying this name does not exist. [That mail server will presumably have its own DNS configuration which will not be the same as the one you've configured internally to pretend that this name exists.] Your postfix setup is using a bogus hostname. mail.eircom.net's SMTP server quite reasonably rejects your mail because your mail server is using that bogus hostname in its outbound SMTP envelope. You have three choices: 1) Make the world's (or just Eircom's) mail servers use your internal DNS configuration. Good luck with that. 2) Configure your mail server to use a domain name that actually exists on the Internet whenever it speaks SMTP to the outside world. 3) Fix your DNS so helen.gayleard.com resolves correctly for everything outside your internal network. It's almost always a mistake to use split DNS setups where an internal name space is not the same as the one used on the public Internet. There are however some circumstances where these setups are unavoidable. I doubt they apply for you. It's also hard to get these configurations right or make them bomb-proof. And when they go wrong -- as appears to have happened here -- internal names "leak" to the public Internet which knows nothing about them. Then boom! > why is helen.gayleard.com not recognized as a local address? Since this name does not resolve in the public DNS it cannot be recognised as any kind of address (hostname) at all.
