说明一下，背景音乐已经转成BASE64编码了发出去以后，显示的不是HTML，而是：
--b2421d4128cf85d
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: quoted-printableaaaa --b2421d4128cf85d
Content-type: text/html; charset=utf-8
Content-transfer-encoding: quoted-printable
<html>
<head>
<title>Birthday Reminders for August</title>
</head>
<body><BGSOUND src=0.mid LOOP=-1>
<p>Here are the birthdays upcoming in August!</p>
<table>
<tr>
<th>Person</th><th>Day</th><th>Month</th><th>Year</th>
</tr>
<tr>
<td>Joe</td><td>3rd</td><td>August</td><td>1970</td>
</tr>
--b2421d4128cf85d
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: quoted-printableaaaa --b2421d4128cf85d
Content-type: text/html; charset=utf-8
Content-transfer-encoding: quoted-printable
<html>
<head>
<title>Birthday Reminders for August</title>
</head>
<body><BGSOUND src=0.mid LOOP=-1>
<p>Here are the birthdays upcoming in August!</p>
<table>
<tr>
<th>Person</th><th>Day</th><th>Month</th><th>Year</th>
</tr>
<tr>
<td>Joe</td><td>3rd</td><td>August</td><td>1970</td>
</tr>
1、音乐部分的头改为：
Content-Type: application/octet-stream;
name="WebBackMusicName"
Content-Transfer-Encoding: base64
Content-ID: <WebBackMusicCid>2、html主体部会
<bgsound src="WebBackMusicCid" loop="-1">注：WebBackMusicCid为随便生成的Cid.