I have a domain which is set up as a site, and it's Mailserver is set to "External Mailserver". There are DNS records on the ISPConfig machine which points the MX to an external mail server and DNS records on the DNS server that my ISPConfig box uses pointing the MX to an external DNS server. However when I send an email to the domain I immediately get an error message from the server: Any idea why it is treating this domain as a local domain when it's definitely set to use an External Mail server?
It's possible that is selected the "External Mailserver" option only for the "www" host: look in the co-domains section and setting the "External Mailserver" for the empty host too (e.g. mydomain.com). In the file /etc/postfix/local-host-names there're the hosts that are considered local (ISPConfig write this file).
