故事是这样的, 因为现在有这样的一个需求,做一个 SMS Proxy 的应用. 理想的使用场景是将一台手机作为固定电话,放在家里,对应的验证码和电话都能转发到其他的一台手机上.电话的话,可以通过呼叫转移实现,但是短信部分,就比较麻烦了,现在有很多的软件都可以实现 SMS Proxy 的功能,但是部分比较复杂,并且因为涉及敏感信息,还是自己开发比较靠谱.

于是,就有了这个一个产品.最理想的逻辑是,在手机端实现一个 callback 函数,当有短信到达时,执行一段代码.考虑到经济原因,理想的转发手段就成了邮件(便宜,实现方便,内容丰富).

于是乎,一个家用的邮件平台就出现了. 这篇博客主要会描述如何实现一个简单的 PHP 后端, 接收对应的数据并通过 Gmail 发送到对应的邮箱中.

为什么 PHP

首先, 家用的信息平台使用 PHP 进行编写, 同时 PHP 易于开发易于部署, 并且我也稍微懂一些代码就使用了.

依托的代码库

PHP 中就有 Mail 函数库, 为什么不直接使用? 其中的一个原因, 就是我不愿意维护一个邮件服务器, 该邮件平台依旧需要支持接收邮件的功能并且 PHP Mail 函数时常爆出漏洞, 结合以上几点, 在这次开发中我使用了 PHPMailer 库.

遇到的坑

Subject 中出现中文乱码

解决办法就是强制指定字符编码为 utf8, 比如使用如下代码:

$mail->Subject = '{YOUR SUBJECT}';
$mail->Subject = "=?UTF-8?B?".base64_encode($mail->Subject)."?=";

邮件内容中文乱码

解决办法就是指定 Body 字符编码, 比如使用如下代码:

$mail->CharSet = "UTF-8";

实现代码

这部分其实是最简单的,以下就是官方给出的代码样例, 结合上面的坑解决办法,就能成功的发出邮件了:

<?php

/**
 * This example shows settings to use when sending via Google's Gmail servers.
 * This uses traditional id & password authentication - look at the gmail_xoauth.phps
 * example to see how to use XOAUTH2.
 * The IMAP section shows how to save this message to the 'Sent Mail' folder using IMAP commands.
 */

//Import PHPMailer classes into the global namespace
use PHPMailer\PHPMailer\PHPMailer;
use PHPMailer\PHPMailer\SMTP;

require '../vendor/autoload.php';

//Create a new PHPMailer instance
$mail = new PHPMailer();

//Tell PHPMailer to use SMTP
$mail->isSMTP();

//Enable SMTP debugging
//SMTP::DEBUG_OFF = off (for production use)
//SMTP::DEBUG_CLIENT = client messages
//SMTP::DEBUG_SERVER = client and server messages
$mail->SMTPDebug = SMTP::DEBUG_SERVER;

//Set the hostname of the mail server
$mail->Host = 'smtp.gmail.com';
//Use `$mail->Host = gethostbyname('smtp.gmail.com');`
//if your network does not support SMTP over IPv6,
//though this may cause issues with TLS

//Set the SMTP port number:
// - 465 for SMTP with implicit TLS, a.k.a. RFC8314 SMTPS or
// - 587 for SMTP+STARTTLS
$mail->Port = 465;

//Set the encryption mechanism to use:
// - SMTPS (implicit TLS on port 465) or
// - STARTTLS (explicit TLS on port 587)
$mail->SMTPSecure = PHPMailer::ENCRYPTION_SMTPS;

//Whether to use SMTP authentication
$mail->SMTPAuth = true;

//Username to use for SMTP authentication - use full email address for gmail
$mail->Username = 'username@gmail.com';

//Password to use for SMTP authentication
$mail->Password = 'yourpassword';

//Set who the message is to be sent from
//Note that with gmail you can only use your account address (same as `Username`)
//or predefined aliases that you have configured within your account.
//Do not use user-submitted addresses in here
$mail->setFrom('from@example.com', 'First Last');

//Set an alternative reply-to address
//This is a good place to put user-submitted addresses
$mail->addReplyTo('replyto@example.com', 'First Last');

//Set who the message is to be sent to
$mail->addAddress('whoto@example.com', 'John Doe');

//Set the subject line
$mail->Subject = 'PHPMailer GMail SMTP test';

//Read an HTML message body from an external file, convert referenced images to embedded,
//convert HTML into a basic plain-text alternative body
$mail->msgHTML(file_get_contents('contents.html'), __DIR__);

//Replace the plain text body with one created manually
$mail->AltBody = 'This is a plain-text message body';

//Attach an image file
$mail->addAttachment('images/phpmailer_mini.png');

//send the message, check for errors
if (!$mail->send()) {
    echo 'Mailer Error: ' . $mail->ErrorInfo;
} else {
    echo 'Message sent!';
    //Section 2: IMAP
    //Uncomment these to save your message in the 'Sent Mail' folder.
    #if (save_mail($mail)) {
    #    echo "Message saved!";
    #}
}

//Section 2: IMAP
//IMAP commands requires the PHP IMAP Extension, found at: https://php.net/manual/en/imap.setup.php
//Function to call which uses the PHP imap_*() functions to save messages: https://php.net/manual/en/book.imap.php
//You can use imap_getmailboxes($imapStream, '/imap/ssl', '*' ) to get a list of available folders or labels, this can
//be useful if you are trying to get this working on a non-Gmail IMAP server.
function save_mail($mail)
{
    //You can change 'Sent Mail' to any other folder or tag
    $path = '{imap.gmail.com:993/imap/ssl}[Gmail]/Sent Mail';

    //Tell your server to open an IMAP connection using the same username and password as you used for SMTP
    $imapStream = imap_open($path, $mail->Username, $mail->Password);

    $result = imap_append($imapStream, $path, $mail->getSentMIMEMessage());
    imap_close($imapStream);

    return $result;
}

如何使用 PHP 通过 Gmail 发送邮件