WordPress Version: 4.6
/**
* Callback to convert email address match to HTML A element.
*
* This function was backported from 2.5.0 to 2.3.2. Regex callback for make_clickable().
*
* @since 2.3.2
* @access private
*
* @param array $matches Single Regex Match.
* @return string HTML A element with email address.
*/
function _make_email_clickable_cb($matches)
{
$email = $matches[2] . '@' . $matches[3];
return $matches[1] . "<a href=\"mailto:{$email}\">{$email}</a>";
}