确定实现方式

读取邮件的协议有POP3和IMAP两种，区别：POP3协议允许电子邮件客户端下载服务器上的邮件，但是在客户端的操作，不会反馈到服务器上。IMAP提供webmail与电子邮件客户端之间的双向通信，客户端的操作都会反馈到服务器上，对邮件进行的操作，服务器上的邮件也会做相应的动作。

需求要求处理完用户的邮件以后，将邮件标记为已处理，因此选用IMAP协议。

安装依赖

本地、服务器php均需要安装imap扩展。在项目的composer.json中添加php-imap(https://github.com/barbushin/php-imap)扩展如下：

"require": {
  "php-imap/php-imap": "^3.1",
},

配置相关服务

namespace app/library/service/mail;

use PhpImap/Exceptions/ConnectionException;
use PhpImap/Mailbox;

/**
 * 收邮件服务邮件API接口
 * Class PlayService
 * @package app/library/service
 */
class ImapService
{
    public $path = '{imap.263.net:993/imap/ssl}INBOX';   // IMAP server and mailbox folder
    public $login = 'user@263.cn';         // Username for the before configured mailbox
    public $password = 'pwd';                   // Password for the before configured username
    public $dir = null;        // Directory, where attachments will be saved (optional)
    public $encoding = 'UTF-8';   // Server encoding (optional)

    public $mailbox;

    public function __construct()
    {
        $this->mailbox = new Mailbox(
            $this->path,
            $this->login,
            $this->password,
            $this->dir,
            $this->encoding
        );
    }

获取所有未读邮件列表

public function unSeenList()
{
    try {
        $mail_ids = $this->mailbox->searchMailbox('UNSEEN');
    } catch (ConnectionException $ex) {
        die('IMAP connection failed: ' . $ex->getMessage());
    } catch (/Exception $ex) {
        die('An error occured: ' . $ex->getMessage());
    }

    // If $mailsIds is empty, no emails could be found
    if (!$mail_ids) {
        die('Mailbox is empty');
    }

    try {
        $info = $this->mailbox->getMailsInfo($mail_ids);
    } catch (ConnectionException $ex) {
        echo "IMAP connection failed: " . $ex;
        die();
    }
    return ['ids' => $mail_ids, 'list' => $info];
}

将某些邮件标记为已读

/**
 * @param array $mail_ids
 * @return mixed
 */
public function markRead($mail_ids)
{
    return $this->mailbox->markMailsAsRead($mail_ids);
}

搜索指定主题的邮件并标记为已读

$imap = new ImapService();
$condition = 'UNSEEN  SUBJECT "' . $title . '" SINCE "' . date('Y-m-d', strtotime('-1 days')) . '" FROM ' . $mail;
$data['mail'] = $imap->mailbox->searchMailbox($condition);
if (!empty($data['mail'])) {
    $data['info'] = $imap->mailbox->getMailsInfo($data['mail']);
    if ($params['mark'] == 1) {
        $data['mark'] = $imap->markRead(array_column($data['info'], 'uid'));
    }
}