Email is sent via curl smtp in php

After the first google test, I found many people who asked relevant questions but had no relevant answers. I also found no relevant classes in phpclasses, so I started to try curl while looking at the relevant protocols of stmp
SMTP agreement
You can find a multi-related example on the Internet. You can use telnet to connect to mail server in experiment 1

 
$ telnet  email SMTP Service address  25 
Trying  Email service IP address ... 
Connected to  email SMTP Service address . 
Escape character is '^]'. 
exchange Email server address  Microsoft ESMTP MAIL Service ready at Sat, 2 Jun 2012 15:02:12 +0800 
EHLO 127.0.0.1 
-exchange Email server address  Hello [ Email service IP address ] 
-SIZE 
-PIPELINING 
-DSN 
-ENHANCEDSTATUSCODES 
-X-ANONYMOUSTLS 
-AUTH NTLM LOGIN 
-X-EXPS GSSAPI NTLM 
-8BITMIME 
-BINARYMIME 
-CHUNKING 
-XEXCH50 
XRDST 
AUTH LOGIN 
VXNlcm5hbWU6 
 The user name (base64_encode) 
UGFzc3dvcmQ6 
 password (base64_encode) 
2.7.0 Authentication successful 
MAIL FROM: Shipping box address  
2.1.0 Sender OK 
RCPT TO: Inbox address  
2.1.5 Recipient OK 
DATA 
Start mail input; end with <CRLF>.<CRLF> 
 Content to send ( There are many related specifications here ) 
. 
2.6.0 <0b476f30-3b96-4e3d-84d2-395a96d34000@exchange Email server address > Queued mail for delivery 
QUIT 
2.0.0 Service closing transmission channel 
Connection closed by foreign host. 

php test code:

 
<?php 
header("content-type:text/html;charset=utf-8"); 
$smtp = array( 
"url" => " email SMTP Server address ", 
"port" => " email SMTP Server port ", // 1 As for the 25 
"username" => " The user name ", 
"password" => " password ", 
"from" => " Send an address ", 
"to" => " Receives an address ", 
"subject" => " test 1 Under the title ", 
"body" => " test 1 The content of " 
); 
$CRLF = "\r\n"; 
$test = ""; 
$curl = curl_init(); 
curl_setopt($curl, CURLOPT_URL, $smtp['url']); 
curl_setopt($curl, CURLOPT_PORT, $smtp['port']); 
curl_setopt($curl, CURLOPT_TIMEOUT,10); 
function inlineCode($str){ 
$str = trim($str); 
return $str?'=?UTF-8?B?'.base64_encode($str).'?= ':''; 
} 
function buildHeader($headers){ 
$ret = ''; 
foreach($headers as $k=>$v){ 
$ret.=$k.': '.$v."\n"; 
} 
return $ret; 
} 
// 
$header = array( 
'Return-path'=>'<'.$smtp['from'].'>', 
'Date'=>date('r'), 
'From'=> '<'.$smtp['from'].'>', 
'MIME-Version'=>'1.0', 
'Subject'=>inlineCode($smtp['subject']), 
'To'=>$smtp['to'], 
'Content-Type'=>'text/html; charset=UTF-8; format=flowed', 
'Content-Transfer-Encoding'=>'base64' 
); 
$data = buildHeader($header).$CRLF.chunk_split(base64_encode($smtp['body'])); 
$content = "EHLO ".$smtp["url"].$CRLF; //  First get hello1 Under the  
$content .= "AUTH LOGIN".$CRLF.base64_encode($smtp["username"]).$CRLF.base64_encode($smtp["password"]).$CRLF; //  Verify landing  
$content .= "MAIL FROM:".$smtp["from"].$CRLF; //  Send an address  
$content .= "RCPT TO:".$smtp["to"].$CRLF; //  Receives an address  
$content .= "DATA".$CRLF.$data.$CRLF.".".$CRLF; //  Send content  
$content .= "QUIT".$CRLF; //  exit  
curl_setopt($curl, CURLOPT_RETURNTRANSFER, true); // curl Receive returned data  
curl_setopt($curl, CURLOPT_CUSTOMREQUEST, $content); 
$test = curl_exec($curl); 
var_dump($test); 
echo "<br/>\r\n"; 
var_dump($content); 
//  The end of the  
curl_close($curl); 

The above is just the php test
Package testing + modification took nearly 6 hours to make the product code fsockopen and curl compatible
Write an smtp class that is compatible with fsockopen and curl to simply send emails