Miscellaneaous Plesk problems and solutions

Currently we don't run any plesk servers ourselves but in the course of our consulting work we were able to solve some problems on customers' plesk servers.

• Plesk - cannot send emails, port 25/587 blocked
• Plesk - php-fpm is configured but fastcgi is served
• Plesk Upgrade - mariadb-server 5.0.60+ required
• Plesk - message cannot be delivered
• Plesk - yum resolve error - duplicate rpm packages
• Unable to find "main" IP address in "psa" database