I finally made it - installed ISPConfig(on top of the "Debian Perfect Se...") Everything seemed to work properly. Web and ftp works well. Then I am in for testing the mail. I send a mail with roundcube webmail. (Have tried with hotmail, gmail and a lot of other mailservices) In /var/log/mail.log this appears when sending a test mail. where "mydomain.net" is a domain I own. However, for me it seems quite right. Can someone tell me why I am not able to send emails?