$to   = "myname@mydomain.com";
  $from = "Gene Z";
  $subj = "my test subject";
  $msg  = "this is the email body";
 
  $file_att_type = "text/calendar; method=REQUEST";
  $file_att_name = "att.ics";
 
  $mime_boundary = "==Multipart_Boundary_x{" . md5(mt_rand()) . "}x";
 
  $header = "From: " . $from . "\r\n" .
            "MIME-Version: 1.0\r\n" .
            "Content-Type: multipart/mixed; boundary=\"{$mime_boundary}\"";
 
  $txt_msg = "this is my text message, to be attached\r\n" .
             "not much to it, eh.";
 
 
  //Various ways to creat a new, random UID
  $cal_uid = "{" . uniqid(mt_rand(), true) . "}";
  $cal_uid = "{" . date('Ymd').'T'.date('His')."-".rand()."@mydomain.com}";
  $cal_uid = com_create_guid();
 
  $msg .= "\nwith uid of $cal_uid\n";
 
  $cal_msg =
"BEGIN:VCALENDAR
PRODID:-//Microsoft Corporation//Outlook 11.0 MIMEDIR//EN
VERSION:2.0
METHOD:REQUEST
BEGIN:VEVENT
ORGANIZER:MAILTO:myname@mydomain.com
DTSTART:20080714T170000Z
DTEND:20080715T035959Z
UID:" . $cal_uid . "
LOCATION:my meeting location
TRANSP:OPAQUE
SEQUENCE:0
DTSTAMP:20060309T045649Z
CATEGORIES:Meeting
DESCRIPTION:meeting description, line 1 of 2.\nline 2 of 2.\n\n
SUMMARY:meeting subject
PRIORITY:5
X-MICROSOFT-CDO-IMPORTANCE:1
CLASS:PUBLIC
BEGIN:VALARM
TRIGGER:-PT3D
ACTION:DISPLAY
DESCRIPTION:Reminder
END:VALARM
BEGIN:VTIMEZONE
TZID:US/Central
END:VTIMEZONE
END:VEVENT
END:VCALENDAR";
 
  $msg = "This is a multi-part message in MIME format.\n\n" .
         "--{$mime_boundary}\n" . 
         "Content-Type: text/plain; charset=\"iso-8859-1\"\n" . 
         "Content-Transfer-Encoding: 7bit\n\n" . 
 
         $msg .
 
         "\n\n--{$mime_boundary}\n" . 
         "Content-Type: $file_att_type; name=$file_att_name\n" . 
         "Content-Disposition: attachment; filename=$file_att_name\n" .
         "Content-Transfer-Encoding: base64\n\n" . 
         chunk_split(base64_encode($cal_msg)) . "\n\n" . 
         "--{$mime_boundary}--\n"; 
 
  if (mail($to, $subj, $msg, $header, "")) {
    echo "test email sent";
  } else {
    echo "test email failed";
  }