If statement optimization - use isset instead of !empty because the request variable is empty if the input field has no value parameter even though the checkbox is activated
from : https://github.com/Kubik-Rubik/joomla-cms/commit/0d851c03f92d16c3fc2d36b5fb374e067f59468e
[bug] Fix - Email copy to own address doesn't work since 2.5.21
Related to bug - [bug] [33848] Fix fatal error when sending contact form
from : https://github.com/Kubik-Rubik/joomla-cms/commit/ab2c509029a3e88977c920dbd74daa1b4a52e761
Merge branch '2.5.22'

* 2.5.22:
  [bug] Fix - Email copy to own address doesn't work since 2.5.21 Related to bug - [bug] [33848] Fix fatal error when sending contact form from : https://github.com/Kubik-Rubik/joomla-cms/commit/ab2c509029a3e88977c920dbd74daa1b4a52e761
  If statement optimization - use isset instead of !empty because the request variable is empty if the input field has no value parameter even though the checkbox is activated from : https://github.com/Kubik-Rubik/joomla-cms/commit/0d851c03f92d16c3fc2d36b5fb374e067f59468e