Installation error Skype click to call

Call installation generate an error , “ An error occurred while applying security settings. Users is not a valid user group. This could be a problem with the package, or a problem connecting to a domain controller on the network. Check your network connection. “ etc.

CentOS + sendmail

Многие сталкивались с проблемой отправки сообщений с сервера из bash/perl/python/php/etc... 
На самом это достаточно просто.