$date = date("F j, Y, g:i a", $sent); 
$log = 'Mailing scheduled for processing on <strong>'.$date.'</strong>. <br>Subject: '.$subject.'<br>Count: '.$count.' recipients. <br>VMID: <strong>'. $vmid .'</strong>.';

Instead of this, i'd propose using this:

$log = 'Mailing scheduled for processing on <strong>'.format_date($sent).'</strong>. <br>Subject: '.$subject.'<br>Count: '.$count.' recipients. <br>VMID: <strong>'. $vmid .'</strong>.';

Otherwise because of the timezone settings, users maybe see weird dates!