Mailq detection

I found that in file Overview.class.php in checkmailq() function the exec command does not correctly formed. If mailq detect that there are no queue, it send to STDERR message "mailq: Mail queue is empty". But the second argument $out of php exec only captures STDOUT from executable and so get the Freepbx error "No response from 'mailq' command".

By default this code is used

$lastline = exec($mailq, $out, $ret);

But more correctly use that

$lastline = exec($mailq.' 2>&1', $out, $ret);