Use PHP to collect POP3 emails (1)_PHP tutorial

Introduction to POP protocol
This article briefly explains the principles of receiving emails and decoding MIME emails through the POP3 protocol. It provides two practical PHP classes for receiving and MIME decoding, and provides examples of use. 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 conversation with the POP3 server Record:
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?=

http://www.bkjia.com/PHPjc/445246.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/445246.htmlTechArticleIntroduction to POP protocol This article briefly explains the principles of receiving emails and decoding MIME emails through the POP3 protocol; for receiving and MIME Decoding, provides two practical PHP classes and provides usage samples...