After executing postmap /etc/postfix/virtusertable that there where 3 duplicate entries within the virtusertable.db. So i opened the file virtusertable and i found out that the usernameA was valid for 3 different domains, like: [email protected] usernameA [email protected] usernameA [email protected] usernameA I removed the duplicate entries from the file virtusertable, but if a new mailuser has been added within ISPConfig, the duplicate entries appear again in the file virtusertable and virtusertable.db. This behaviour shows me that there must be something wrong with the ISPConfig2 database, but i can not find out what. Also within ISPConfig itself, i can not find anything related. Can anyone tell me what to do to solve this problem?