探索smtp协议
百度百科
简单邮件传输协议(SMTP )是一种简单的邮件传输协议,它是一组用于将邮件从源地址传输到目标地址的规则,用于控制中继消息的方式。 SMTP协议属于TCP/IP协议群集,可以帮助每台计算机在发送或中继消息时找到以下目标。 可以通过SMTP协议指定的服务器将电子邮件发送到收件人的服务器。 整个过程只需要几分钟。 SMTP服务器是符合SMTP协议的发送邮件服务器,用于发送或中继发送的电子邮件。
(传送门)
客户端和邮件服务器的交互过程
连接和发送邮件的步骤如下。
)1) TCP连接的建立;
)2)客户端发送HELO命令以识别发件人,服务器将OK作为回复,表示准备接收
)3)使用AUTH命令登录到SMTP服务器,输入用户名和密码(用户名和密码用base64加密);
(4)客户端发送MAIL命令,输入发送者的邮件地址,服务器将OK作为应答
)5)客户端发送RCPT命令,识别该电子邮件的预定收件人,服务器以OK为响应;
(6)协议结束后,使用DATA命令发送;
)7)以“.”结束,输入内容一起发送,
)8)结束本次发送,用QUIT命令结束。
PHPmailer发送示例
2017-06-1614336029336013服务器客户端:220晕圈
2017-06-1614336029336013客户端服务器:嵌入式电脑
2017-06-1614336029336013服务器客户端:250-localhosthelloehloheqian-PC
250-SIZE 131072
250 -拼音
250 -自动平面登录
250帮助
2017-06-1614336029336013客户端-服务器:授权
2017-06-1614336029336013 server-client :334 vxn lcm5 hbwu=
2017-06-1614336029336013客户端服务器:
2017-06-1614336029336013 server-client :334 ug FZ c3dv cmq=
2017-06-1614336029336013客户端服务器:
2017-06-1614336029336013服务器-客户端:235身份验证
2017-06-1614336029336013客户端服务器:邮件来自:
2017-06-1614336029336013服务器-客户端:250确定
2017-06-1614336029336013客户端服务器: rcpt to :
2017-06-1614336029336013服务器-客户端:250确定
2017-06-1614336029336013客户端服务器:数据
2017-06-1614336029336013服务器-客户端3360354最终数据宽度。
2017-06-1614336029336013客户端-服务器:数据: fri,16 Jun 2017 14:29:13 0000
2017-06-1614336029336013客户端服务器: to : fage 1151 @ QQ.com
2017-06-1614336029336013客户端-服务器: from :=? utf-8? B? 5piT6IGU5LqR?=
2017-06-1614336029336013客户端服务器: reply-to :=? utf-8? B? 5piT6IGU5LqR?= 1151878751@qq.com
2017-06-1614336029336013客户端-服务器:子对象:=? utf-8? B? 5piT6IGU5LqR6aqM6K B56CB?=
2017-06-1614336029336013客户端服务器:消息id :
2017-06-1614336029336013客户端服务器: x-mailer : phpmailer 5.2.23653https://github.com/phpmailer/phpmailer
2017-06-1614336029336013客户端服务器: mime-ve
rsion: 1.02017-06-16 14:29:13 CLIENT -> SERVER: Content-Type: multipart/alternative;
2017-06-16 14:29:13 CLIENT -> SERVER: boundary="b1_a2430819ef128b7b55181b6ebd2e021e"
2017-06-16 14:29:13 CLIENT -> SERVER: Content-Transfer-Encoding: 8bit
2017-06-16 14:29:13 CLIENT -> SERVER:
2017-06-16 14:29:13 CLIENT -> SERVER: This is a multi-part message in MIME format.
2017-06-16 14:29:13 CLIENT -> SERVER:
2017-06-16 14:29:13 CLIENT -> SERVER: --b1_a2430819ef128b7b55181b6ebd2e021e
2017-06-16 14:29:13 CLIENT -> SERVER: Content-Type: text/plain; charset=utf-8
2017-06-16 14:29:13 CLIENT -> SERVER: Content-Transfer-Encoding: 8bit
2017-06-16 14:29:13 CLIENT -> SERVER:
2017-06-16 14:29:13 CLIENT -> SERVER: 你好 smtp
2017-06-16 14:29:13 CLIENT -> SERVER:
2017-06-16 14:29:13 CLIENT -> SERVER:
2017-06-16 14:29:13 CLIENT -> SERVER: --b1_a2430819ef128b7b55181b6ebd2e021e
2017-06-16 14:29:13 CLIENT -> SERVER: Content-Type: text/html; charset=utf-8
2017-06-16 14:29:13 CLIENT -> SERVER: Content-Transfer-Encoding: 8bit
2017-06-16 14:29:13 CLIENT -> SERVER:
2017-06-16 14:29:13 CLIENT -> SERVER:
你好 smtp2017-06-16 14:29:13 CLIENT -> SERVER:
2017-06-16 14:29:13 CLIENT -> SERVER:
2017-06-16 14:29:13 CLIENT -> SERVER:
2017-06-16 14:29:13 CLIENT -> SERVER: --b1_a2430819ef128b7b55181b6ebd2e021e--
2017-06-16 14:29:13 CLIENT -> SERVER:
2017-06-16 14:29:13 CLIENT -> SERVER: .
2017-06-16 14:29:13 SERVER -> CLIENT: 250 ok:queued as
2017-06-16 14:29:13 CLIENT -> SERVER: QUIT
2017-06-16 14:29:13 SERVER -> CLIENT: 221 Bye
跨邮件服务器之间的通信
连接和投递步骤如下:
(1)建立TCP连接;
(2)服务器发送HELO命令以标识发件人的身份,目标服务器以OK作为响应,表明准备接收;
(3)服务器发送MAIL 命令输入发件人邮箱地址,目标服务器以OK作为响应;
(4)服务器发送RCPT命令,标识该电子邮件的计划接收人,目标服务器以OK作为响应;
(5)协商结束后,使用DATA命令发送;
(6)以"."号表示结束,输入内容一起发送出去,
(7)结束此次发送,用QUIT命令退出。
PHPmailer发送示例
2017-06-16 14:24:41 SERVER -> CLIENT: 220 hello
2017-06-16 14:24:41 CLIENT -> SERVER: EHLO heqian-pc
2017-06-16 14:24:41 SERVER -> CLIENT: 250-localhost Hello EHLO heqian-pc
250-SIZE 131072
250-PIPELINING
250 HELP
2017-06-16 14:24:41 CLIENT -> SERVER: MAIL FROM:
2017-06-16 14:24:41 SERVER -> CLIENT: 250 Ok
2017-06-16 14:24:41 CLIENT -> SERVER: RCPT TO:
2017-06-16 14:24:41 SERVER -> CLIENT: 250 Ok
2017-06-16 14:24:41 CLIENT -> SERVER: DATA
2017-06-16 14:24:41 SERVER -> CLIENT: 354 End data with .
2017-06-16 14:24:41 CLIENT -> SERVER: Date: Fri, 16 Jun 2017 14:24:41 +0000
2017-06-16 14:24:41 CLIENT -> SERVER: To: fage1151@qq.com
2017-06-16 14:24:41 CLIENT -> SERVER: From: =?utf-8?B?5piT6IGU5LqR?=
2017-06-16 14:24:41 CLIENT -> SERVER: Reply-To: =?utf-8?B?5piT6IGU5LqR?= <1151878751@qq.com>
2017-06-16 14:24:41 CLIENT -> SERVER: Subject: =?utf-8?B?5piT6IGU5LqR6aqM6K+B56CB?=
2017-06-16 14:24:41 CLIENT -> SERVER: Message-ID: <6fc893187701010670b0d152b2d954f6@heqian-pc>
2017-06-16 14:24:41 CLIENT -> SERVER: X-Mailer: PHPMailer 5.2.23 (https://github.com/PHPMailer/PHPMailer)
2017-06-16 14:24:41 CLIENT -> SERVER: MIME-Version: 1.0
2017-06-16 14:24:41 CLIENT -> SERVER: Content-Type: multipart/alternative;
2017-06-16 14:24:41 CLIENT -> SERVER: boundary="b1_6fc893187701010670b0d152b2d954f6"
2017-06-16 14:24:41 CLIENT -> SERVER: Content-Transfer-Encoding: 8bit
2017-06-16 14:24:41 CLIENT -> SERVER:
2017-06-16 14:24:41 CLIENT -> SERVER: This is a multi-part message in MIME format.
2017-06-16 14:24:41 CLIENT -> SERVER:
2017-06-16 14:24:41 CLIENT -> SERVER: --b1_6fc893187701010670b0d152b2d954f6
2017-06-16 14:24:41 CLIENT -> SERVER: Content-Type: text/plain; charset=utf-8
2017-06-16 14:24:41 CLIENT -> SERVER: Content-Transfer-Encoding: 8bit
2017-06-16 14:24:41 CLIENT -> SERVER:
2017-06-16 14:24:41 CLIENT -> SERVER: 你好 smtp
2017-06-16 14:24:41 CLIENT -> SERVER:
2017-06-16 14:24:41 CLIENT -> SERVER:
2017-06-16 14:24:41 CLIENT -> SERVER: --b1_6fc893187701010670b0d152b2d954f6
2017-06-16 14:24:41 CLIENT -> SERVER: Content-Type: text/html; charset=utf-8
2017-06-16 14:24:41 CLIENT -> SERVER: Content-Transfer-Encoding: 8bit
2017-06-16 14:24:41 CLIENT -> SERVER:
2017-06-16 14:24:41 CLIENT -> SERVER:
你好 smtp2017-06-16 14:24:41 CLIENT -> SERVER:
2017-06-16 14:24:41 CLIENT -> SERVER:
2017-06-16 14:24:41 CLIENT -> SERVER:
2017-06-16 14:24:41 CLIENT -> SERVER: --b1_6fc893187701010670b0d152b2d954f6--
2017-06-16 14:24:41 CLIENT -> SERVER:
2017-06-16 14:24:41 CLIENT -> SERVER: .
2017-06-16 14:24:41 SERVER -> CLIENT: 250 ok:queued as
2017-06-16 14:24:41 CLIENT -> SERVER: QUIT
2017-06-16 14:24:41 SERVER -> CLIENT: 221 Bye
是不是发现邮件服务器之间和客户端与邮件服务器之间的协议是如此的相似呢。
他们有什么区别呢。
一般情况下,客户端与服务器交互是通过一个域名实现的,例如:smtp.qq.com,smtp.163.com,smtp.sina.cn
而邮箱服务器之间一般是通过邮箱后缀的mx邮件交换记录来完成的。如何查看邮件服务器的mx记录