Using PHP to collect POP3 emails_PHP tutorial

Introduction to POP protocol (Author: Chen Junqing, October 18, 2000 11:53) This article briefly explains the principle of receiving emails and decoding MIME emails through the POP3 protocol; for receiving and MIME decoding, two practical PHP classes are provided, and Examples of usage are provided. It is divided into two parts: mail collection and MIME decoding. Here we will first introduce you to the collection of emails. The decoding part will be introduced in detail in future articles, so stay tuned. The biggest application on the Internet now is probably Email. We are used to communicating through Email every day, and almost all major websites have launched their own free email systems based on WEB. In this article, the author will introduce some principles of Email implementation. At the same time, we assume that you have a certain foundation in PHP programming and a certain understanding of the TCP/IP protocol. Introduction to POP protocol The full name of POP is Post Office Protocol, which is the post office protocol and is used for receiving emails. The third version is commonly used now, referred to as POP3. Through the POP protocol, after the client logs in to the server, it can delete its own emails or download them locally. After downloading, the email client software can modify and delete the emails locally. Another type of email used to receive letters is the IMAP protocol, which is developing very quickly and we will not discuss it in this article. POP servers generally use TCP port 110. If you are using Foxmail, when it receives mail, you can see the following commands in its information prompt window: "Connecting to 62.123.23.123:110" ; "USER BOSS_CH"; "PASS............"; Let's take a look at a transcript of the conversation with the POP3 server: telenet pop.china.com 110 +OK AIMC POP service ( mail2.china.com) is ready. USER boss_ch +OK Please enter password for user . PASS ****** +OK boss_ch has 1 messages (750 octets) STAT +OK 1 750 LIST +OK 1 messages ( 750 octets) 　1 750 　RETR 1 　+OK 750 octets 　Received: from smtp2.ptt.js.cn([202.102.24.37]) by china.com(JetMail 2.5.3.0) 　　with SMTP id jm4839cc4227; Sat, 23 Sep 2000 05: 31:21 -0000 　Received: from chenjunqing ([61.155.120.6]) by smtp2.ptt.js.cn 　　(Netscape Messaging Server 4.15) with SMTP id G1BRHJ03.V07 for 　　; Sat, 23 Sep 2000 13:34: 31 +0800 　Date: Sat, 23 Sep 2000 13:34:18 +0800 　From: =?ISO-8859-1?Q?=B3=C2=BF=A1=C7=E5?= 　To: boss_ch@ china.com 　Subject: =?ISO-8859-1?Q?=D3=CA=BC=FE=CA=BE=C0=FD?= 　X-mailer: FoxMail 3.1 [cn] 　Mime-Version: 1.0 Content-Type: text/plain; charset="GB2312" Content-Transfer-Encoding: 8bit Message-ID: Hello! This is a small example of an email QUIT +OK Pop server at signing off. The following is a brief introduction to several commonly used POP3 commands: Command parameter status description------------- -------------------------- USER username Approval of this command and the following pass command, if successful, will result in state transition PASS Password Approval of APOP Name,Digest recognizes that Digest is the MD5 message digest----------------------------------------- - STAT　None 　Processing the request server to send back statistical information about the mailbox, such as the total number of messages and the total number of bytes UIDL 　　　[Msg#] 　　Processing the unique identifier of the returned email, each identifier of the POP3 session will be a unique LIST　　[Msg #] Processing returns the number of emails and the size of each email RETR [Msg#] Processing returns the entire text of the email identified by the parameter DELE [Msg#] Processing server marks the email identified by the parameter as deleted, executed by the quit command RSET None Processing The server will reset all messages marked for deletion, used to undo the DELE command TOP [Msg#] The processing server will return the first n lines of the message identified by the parameter, n must be a positive integer NOOP None The processing server returns a positive response, no Do any operation. ​------------------------------------------------ ​QUIT ​None ​Update Exit