Hi! I have a tricky problem with my mail-server on ISPConfig. I have set up four domains: - test1.com - test2.com - test3.com - test4.com test1.com is one site. In test1.com's settings I have added test2.com under "Co-domains". So test1.com and test2.com goes to the same account. Then I want to forward all mail from test1.com and test2.com to test3.com. So under advanced settings on test1.com (also test2.com), my forwarding mail is [email protected]. When I send mail from [email protected] to [email protected] it is no problem. But when I send mail from [email protected] to test1.com or test2.com I get the following mail in return: Code: This is the Postfix program at host test4.com. I'm sorry to have to inform you that your message could not be delivered to one or more recipients. It's attached below. For further assistance, please send mail to <postmaster> If you do so, please include this problem report. You can delete your own text from the attached returned message. The Postfix program <[email protected] Anyone that can help me, please?