Hello again, I have the following scenario for my ISPConfig server: I have a domain - domain.com. The dns servers for this domain are not related to my ISPConfig. The ISPConfig host name is ns1.domain.com. All domains that are in its DNS work fine and mail too. Now the issue I have is: I set up in the external dns www.domain.com for my domain to be pointed to my ISPConfig machine. The website is working fine. I also have an EXTERNAL MAILSERVER for this domain and it is working fine, except when I try to send email using ISPConfig machine as relay. I set the www.domain.com to use EXTERNAL MAILSERVER as well as the co-domain domain.com. But I still get 'loops back to myself' error. This is what I have in /etc/postfix/local-host-names for my domain ns1.smartcall.bg localhost.ns1.smartcall.bg localhost.smartcall.bg - this, I believe shouldn't be here localhost.localdomain A long story. Hope somebody will read. Thanks!