How to disable PHP functions globally via Plesk?
E.g. in order to restrict PHP mail() functionality.
Note: Instructions below are for the default Plesk installation with vanilla PHP. It will not work for the Plesk with CageFS or Alt-PHP.
Disabling PHP functions is possible on a handler level. To achieve this, perform the following:
Log into Plesk and go to Tools & Settings > General Settings > PHP Settings;
Choose PHP handler which settings you wish to modify:
Switch to tab php.ini and find the directive
Append to the line functions so it looks like this:
disable_functions = exec, system, mail
Save the changes by clicking OK.