[Cyricx]

Like so

// this grabs an overview of all the messages in the mailbox and creates an array we can read
  $letters = imap_fetch_overview($mailbox,"1:$amountmessages",0);
 
//then later in the cron file it checks the array we made above and determines the sender and host to determine the email address.
   $fromaddress = $letter->sender[0]->mailbox ."@".$letter->sender[0]->host;
 
// then later it does this query to find a user that has that email address
   $userinfo = $vbulletin->db->query_first("
    SELECT user.*, usertextfield.*
    FROM " . TABLE_PREFIX . "user AS user
    LEFT JOIN " . TABLE_PREFIX . "usertextfield AS usertextfield ON (usertextfield.userid = user.userid)
    WHERE email = '".addslashes(htmlspecialchars($fromaddress))."'
   ");
 
// finally in the cron file it does this which is where if there is not a user found in the above query, it sends the person an error message.
 
   // If Email Address belongs to a user
   if (!$userid)
   {
    $userinfo['username'] = "Unregistered User";
      $userinfo['languageid'] = 0;
    eval(fetch_email_phrases('ei_error_nouser', $userinfo['languageid']));
    vbmail($fromaddress, $subject, $message);
    imap_delete($mailbox,$msgno);
    continue;
   }

You guys are killin me here

I think I've mentioned this a few times in this thread how it determines the user that is posting