Q 什么是MIME?什么是MIME邮件?
A MIME, 全称为“Multipurpose Internet Mail Extensions”, 比较确切的中文名称为“多用途互联网邮件扩展”。它是当前广泛应用的一种电子邮件技术规范,基本内容定义于RFC 2045-2049。
自然,MIME邮件就是符合MIME规范的电子邮件,或者说根据MIME规范编码而成的电子邮件。
在MIME出台之前,使用RFC 822只能发送基本的ASCII码文本信息,邮件内容如果要包括二进制文件、声音和动画等,实现起来非常困难。MIME提供了一种可以在邮件中附加多种不同编码文件的方法,弥补了原来的信息格式的不足。实际上不仅仅是邮件编码,现在MIME经成为HTTP协议标准的一个部分。
下面举几个MIME邮件的例子,让我们先对MIME编码的格式有个直观的印象。例1是最简单的,只带纯文本正文,基本上就是RFC 822格式;例2复杂一些,包含纯文本和超文本正文;例3是最复杂的,包含纯文本正文、超文本正文、内嵌资源和文件附件。其中,行号和行号后的空格是为了分析方便而另外加的,“... ... ... ...”表示此处省略了大段编码。
例1
1 Date: Thu, 18 Apr 2002 09:32:45 +0800
2 From: <bhw98@sina.com>
3 To: <bhwang@jlonline.com>
4 Subject: Test
5 Mime-Version: 1.0
6 Content-Type: text/plain; charset="iso-8859-1"
7
8 This is a simple mail.
9
例2
1 From: "bhw98" <bhw98@sina.com>
2 Reply-To: bhw98@sina.com
3 To: <bluesky7810@163.com>
4 Subject: Re: help
5 X-Mailer: Foxmail 4.2 [cn]
6 Mime-Version: 1.0
7 Content-Type: multipart/alternative;
8 boundary="=====002_Dragon307572345230_====="
9
10
11 This is a multi-part message in MIME format.
12
13 --=====002_Dragon307572345230_=====
14 Content-Type: text/plain; charset="GB2312"
15 Content-Transfer-Encoding: quoted-printable
16
17 bluesky7810=A3=AC=C4=FA=BA=C3=A3=A1
18
19 =A1=A1=A1=A1=D4=DA=CF=C2=C6=AA=D7=EE=BA=F3=BF=C9=D2=D4=CF=C2=D4=D8=B0=A1=A3=AC=C4=E3
... ... ... ...
30 =A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A1=A12003-04-07
31
32 --=====002_Dragon307572345230_=====
33 Content-Type: text/html; charset="GB2312"
34 Content-Transfer-Encoding: quoted-printable
35
36 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
37 <HTML><HEAD>
38 <META content=3D"text/html; charset=3Dgb2312"=
39 http-equiv=3DContent-Type>
40 <META content=3D"MSHTML 5.00.2920.0" name=3DGENERATOR>
... ... ... ...
79 </HTML>
80
81 --=====002_Dragon307572345230_=====--
82
例3
1 Return-Path: <bluesky7810@163.com>
2 Delivered-To: bhw98@sina.com
3 Received: (qmail 75513 invoked by alias); 20 May 2002 02:19:53 -0000
4 Received: from unknown (HELO bluesky) (61.155.118.135)
5 by 202.106.187.143 with SMTP; 20 May 2002 02:19:53 -0000
6 Message-ID: <007f01c3111c$742fec00$0100007f@bluesky>
7 From: "=?gb2312?B?wLbAtrXEzOwNCg==?=" <bluesky7810@163.com>
8 To: "bhw98" <bhw98@sina.com>
9 Cc: <bhwang@jlonline.com>
10 Subject: =?gb2312?B?ztK1xLbgtK6/2rPM0PI=?=
11 Date: Sat, 20 May 2002 10:03:36 +0800
12 MIME-Version: 1.0
13 Content-Type: multipart/mixed;
14 boundary="----=_NextPart_000_007A_01C3115F.80DFC5E0"
15 X-Priority: 3
16 X-MSMail-Priority: Normal
17 X-Mailer: Microsoft Outlook Express 5.00.2919.6700
18 X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2919.6700
19
20 This is a multi-part message in MIME format.
21
22 ------=_NextPart_000_007A_01C3115F.80DFC5E0
23 Content-Type: multipart/related; type="multipart/alternative";
24 boundary="----=_NextPart_001_007B_01C3115F.80DFC5E0"
25
26
27 ------=_NextPart_001_007B_01C3115F.80DFC5E0
28 Content-Type: multipart/alternative;
29 boundary="----=_NextPart_002_007C_01C3115F.80DFC5E0"
30
31 ------=_NextPart_002_007C_01C3115F.80DFC5E0
32 Content-Type: text/plain; charset="gb2312"
33 Content-Transfer-Encoding: quoted-printable
34
35 bhw98, =C4=E3=BA=C3!
36 =D5=E2=CA=C7=CE=D2=D0=B4=B5=C4=B6=E0=B4=AE=BF=DA=CD=A8=D0=C5=B5=C4=B3=CC=D0=
37 =F2, =C7=EB=D6=B8=BD=CC