The control panel does not send data from the administration

For example, if I create a new database and want to have the login details sent to my e-mail, the e-mail will probably not be sent.

Check if you see something in /var/log/exim4/mainlog

See otherwise:

Hi, in log file is no activity.

root@server:/var/log/exim4# hostnamectl status
Static hostname: server
Icon name: computer-container
Machine ID: xxx
Boot ID: xxx
Virtualization: lxc
Operating System: Debian GNU/Linux 9 (stretch)
Kernel: Linux 5.10.54
Architecture: x86-64

But the mail server works normally.

So far I have not been able to investigate the issue yet. When I have time I will look into it…