lib/mail/Mail.php
public function addCategory($category)
    {
        if (!($category instanceof Category)) {
            $category = new Category($category);
        }
        $this->categories[] = $category;
    }
public function addCategory($category)
    {
        if (!($category instanceof Category)) {
            $category = new Category($category);
        }
        $this->categories[] = $category;
    }
public function addCategory ( $ category ) { if ( ! ( $ category instanceof Category ) ) { $ category = new Category ( $ category ) ; } $ this -> categories [ ] = $ category ; }
Add a category to a Mail object

@param string|Category $category Category object or category name
Add a category to a Mail object