Use PHP to decode POP3 emails (1)_PHP Tutorial

A preliminary understanding of the source files of emails
This article briefly explains the principles of receiving emails through the POP3 protocol and decoding MIME emails; 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. We have already introduced you to the collection of emails, now let us introduce you to the decoding part of this article.
In the previous article, we have completed an example of using PHP to receive emails through POP3. However, when using this class, I believe you have seen that many emails received are a bunch of garbled characters, and you can’t even read them. don't know! Yes. Most of today's emails have been encoded and require a decoding process before they can be turned into the text, pictures, or other attachments we are used to.
The source file of the email
First, let’s take a look at the source file of a simple email: (In Foxmail, select the email and click “View Source File” to see something like this)
From:
To:
Subject: =?gb2312?B?xOO6w6Oh?=
Date: Sun, 8 Oct 2000 20:28:45 +0800
MIME-Version: 1.0
Content-Type: multipart/alternative;
boundary="----=_NextPart_000_0007_01C03166.5B1E9510"
X-Priority: 3
X-MSMail-Priority: Normal
X-Mailer: Microsoft Outlook Express 5.00.2919.6700
X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2919.6700
This is a multi-part message in MIME format. > Content-Type: text/plain;
charset="gb2312"
Content-Transfer-Encoding: base64
w7vT0MLSwuuwyaO/DQo=
-------=_NextPart_000_0007_01C03166.5B1E9510
Content -Type: text/html;
charset="gb2312"
Content-Transfer-Encoding: base64
PCFET0NUWVBFIEhUTUwgUFVCTElDICItLy9XM0MvL0RURCBIVE1MIDQuMCBUcmFuc2l0aW9uYWwv
L0VOIj 4NCjxIVE1MPjxIRUFEPg0KPE1FVEEgY29udGVudD0idGV4dC9odG1sOyBjaGFyc2V0PWdi NS4w
MC4yOTIwLjAiIG5hbWU9R0VORVJBVE9SPg0KPFNUWUxFPjwvU1RZTEU+DQo8L0hFQUQ+DQo8Qk9E
WSBiZ0NvbG9yPSNmZmZmZmY+DQo8RElWPjxGT05UIHNpemU9Mj7Du9PQwtLC67DJo788L0ZPTlQ+
　PC9ESVY+PC9CT0RZPjwvSFRNTD4NCg==