Errors when starting work with the panel

After installing the panel, the first error is with the host, it is impossible to create a website, error - Blacklisted domain.
Fixed this error thanks to this guide, it turned out to create a site (
But why should I do it? Why doesn’t it work out of the box?

Then I was unable to access my mailbox via snappymail, error - AUTHENTICATIONFAILED Authentication failed

A few months ago this was not the case. Everything worked great. Now no, regardless of the OS, on the Cent OS, Ubuntu of different versions - the same errors.
The work of a this panel tester is annoying, how can this be released into production