Telnet sends emails to multiple addresses.

////////////////////////////////////////////////////////////  
//   EmailClass 0.5  
//   class for sending mail  
//  
//   Paul Schreiber  
//   php@paulschreiber.com  
//   http://paulschreiber.com/  
//  
//   parameters  
//   ----------  
//   - subject, message, senderName, senderEmail and toList are required  
//   - ccList, bccList and replyTo are optional  
//   - toList, ccList and bccList can be strings or arrays of strings  
//     (those strings should be valid email addresses  
//  
//   example  
//   -------  
//   $m = new email ( "hello there",            // subject  
//                    "how are you?",           // message body  
//                    "paul",                   // sender's name  
//                    "foo@foobar.com",         // sender's email  
//                    array("paul@foobar.com", "foo@bar.com"), // To: recipients  
//                    "paul@whereever.com"      // Cc: recipient  
//                   );  
//  
//       print "mail sent, result was" . $m->send();  
//  
//  
//  
if ( ! defined( 'MAIL_CLASS_DEFINED' ) ) {  
        define('MAIL_CLASS_DEFINED', 1 );  
class email {  
        // the constructor!  
        function email ( $subject, $message, $senderName, $senderEmail, $toList, $ccList=0, $bccList=0, $replyTo=0) {  
                $this->sender = $senderName . " <$senderEmail>";  
                $this->replyTo = $replyTo;  
                $this->subject = $subject;  
                $this->message = $message;  
                // set the To: recipient(s)  
                if ( is_array($toList) ) {  
                        $this->to = join( $toList, "," );  
                } else {  
                        $this->to = $toList;  
                }  
                // set the Cc: recipient(s)  
                if ( is_array($ccList) && sizeof($ccList) ) {  
                        $this->cc = join( $ccList, "," );  
                } elseif ( $ccList ) {  
                        $this->cc = $ccList;  
                }  
                // set the Bcc: recipient(s)  
                if ( is_array($bccList) && sizeof($bccList) ) {  
                        $this->bcc = join( $bccList, "," );  
                } elseif ( $bccList ) {  
                        $this->bcc = $bccList;  
                }  
        }  
        // send the message; this is actually just a wrapper for   
        // PHP's mail() function; heck, it's PHP's mail function done right :-)  
        // you could override this method to:  
        // (a) use sendmail directly  
        // (b) do SMTP with sockets  
        function send () {  
                // create the headers needed by PHP's mail() function  
                // sender  
                $this->headers = "From: " . $this->sender . "n";  
                // reply-to address  
                if ( $this->replyTo ) {  
                        $this->headers .= "Reply-To: " . $this->replyTo . "n";  
                }  
                // Cc: recipient(s)  
                if ( $this->cc ) {  
                        $this->headers .= "Cc: " . $this->cc . "n";  
                }  
                // Bcc: recipient(s)  
                if ( $this->bcc ) {  
                        $this->headers .= "Bcc: " . $this->bcc . "n";  
                }
                                                                                                                                                                                , Return mail ($this->to, $this->subject, $this->message, $this->headers);
The above has introduced the class of sending emails through telnet to multiple addresses, including the content of sending emails through telnet. I hope it will be helpful to friends who are interested in PHP tutorials.