I upgraded Ubuntu 8.10 to Ubuntu 9.04, a server running with ISPconfig 126.96.36.199 Now I have a mail receiving problem. Looks like this: This is the mail system at host server1.example.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 mail system <email@example.com>: user unknown. Command output: ERR: authdaemon: s_connect() failed: Permission denied Invalid user specified. When I had Ubuntu 8.10 running with ISPconfig 3.0.1, I had the same problem, but it solved when I updated to ISPconfig 188.8.131.52. Now that I updated Ubuntu too, the problem is back. What should I do so that I could receive mail?