邮件接收时解码的问题.

接收一封邮件,它的原信息如下:
X-Uidl: 1254116980.25659.0&&pop3.sina.com.cn
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Date: Mon, 28 Sep 2009 13:49:40 +0800 
From: [email protected]
Subject: =?GB2312?B?u7bTrcq508PQwsDLw+K30dPKz+Q=?=
To: [email protected]
Mime-Version: 1.0
Content-type: text/html; charset=utf-8
Content-transfer-encoding: 8BIT
X-Mailer: SinaMail 3.0
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>鏃犳爣棰樻枃妗?/title>
<style type="text/css">
table {
border: 1px solid #729bc2;
}
</style>
<style type="text/css">
.td1 {
padding-top: 35px;
padding-right: 33px;
padding-bottom: 35px;
padding-left: 23px;
list-style-image: url(http://www.sinaimg.cn/rny/sinamail50/images/eml/01.gif);
}
.title {
font-family: "榛戜綋";
font-size: 18px;
line-height: 47px;
color: #2B75BC;
}
</style>
<style type="text/css">
.text {
font-family: "Arial", "瀹嬩綋";
font-size: 15px;
line-height: 26px;
color: #000000;
}
.title2 {
font-family: "瀹嬩綋";
font-size: 15px;
font-weight: bold;
color: #2C75BB;
}
.list {
font-family: "Arial", "瀹嬩綋";
font-size: 15px;
line-height: 26px;
color: #000000;
list-style-image: url(http://www.sinaimg.cn/rny/sinamail50/images/eml/01.gif);
}
.colortext {
color: #2C75BB;
}
</style>
</head><body>
<table width="720" border="0" cellspacing="0" cellpadding="0">
  <tr>
    <td><img src="http://www.sinaimg.cn/rny/09free/logo/09welcome718_1.jpg" width="718" height="50"></td>
  </tr>
  <tr class="text"> 
    <td class="td1"><p><span class="title">灏婃暚鐨勭敤鎴凤紝鎰熻阿鎮ㄩ€夋嫨鏂版氮閭锛?/span></p>
      <p >鎮ㄧ殑鐢靛瓙閭锛?span class="colortext">[email protected]</span>锛屽凡缁忔垚鍔熷紑閫氥€傛柊娴偖绠卞叏浣撳伐浣滀汉鍛樼儹蹇变负鎮ㄦ彁渚涚ǔ瀹氥€佸畨鍏ㄣ€佸揩鎹风殑閭欢閫氫俊鏈嶅姟锛岃鎮ㄤ韩鍙楁棤闄愮殑娌熼€氫箰瓒ｃ€?/p>
      <p>闄や簡鍩虹鐨勯偖浠舵敹銆佸彂鍔熻兘锛屾柊娴偖绠辨洿涓烘偍鎻愪緵锛?/p>
      <p> <span class="title2">绠€渚垮疄鐢ㄧ殑閭欢绠＄悊</span></p>
      <ul>
        <li> 鏈閭欢鎻愮ず锛屽府鎮ㄥ強鏃跺鐞嗘潵淇°€?</li>
        <li> 鏍规嵁鎮ㄧ殑鍠滃ソ锛屽彲閫夋嫨鎸夋椂闂淬€佽仈绯讳汉銆佷富棰樼瓑鏂瑰紡鍒嗙被鏄剧ず鏉ュ線閭欢銆?</li>
        <li> 鍙垱寤鸿嚜宸辩殑閭欢澶瑰垎绫讳繚瀛橀噸瑕侀偖浠躲€?</li>
        <li> 浠ｆ敹鍏跺畠甯愬彿鐨勯偖绠憋紝鏂逛究鎮ㄧ粺涓€绠＄悊鍏ㄩ儴閭欢銆?</li>
      </ul>
      <p><span class="title2">涓板瘜澶氬僵鐨勯偖浠跺舰寮?/span></p>
      <ul>
        <li> 鍥剧墖銆佽〃鎯呫€佷俊绾镐互鍙婂己澶х殑鏂囨湰缂栬緫鍔熻兘璁╂偍鐨勯偖浠跺厖婊℃儏瓒ｏ紝鍒叿涓€鏍笺€?</li>
        <li> 闅忎俊鍙彂閫?5M鐨勯檮浠讹紝璁╂偍鐨勬枃浠跺垎浜洿鍔犲畨鍏ㄥ揩鎹枫€?</li>
      </ul>
      <p><span class="title2">杞绘澗蹇嵎鐨勮仈绯讳汉绠＄悊</span></p>
      <ul>
        <li> 鍙戦偖浠舵椂鑷姩淇濆瓨鑱旂郴浜哄湴鍧€銆?</li>
        <li> 绠€鍗曟柟渚跨殑閫氳褰曡皟鐢紝璁╂偍缁欒仈绯讳汉鍐欎俊鏇磋交鏉俱€?</li>
        <li> 鐏垫椿鐨勮仈绯讳汉鍒嗙粍锛屽姪鎮ㄩ珮鏁堢鐞嗘洿澶氳仈绯讳汉銆?/li>
      </ul>
      <p>娆茶缁嗕簡瑙ｆ洿澶氬姛鑳斤紝璇锋煡鐪?a href="http://mail.sina.com.cn/help2/helpcenter.html" target="_blank">鏇村甯姪&gt;&gt;</a><br>
        濡傛偍閬囧埌闂锛岃鑷寸數鏂版氮瀹㈡湇锛?5105670 鎴?a href="http://comment4.news.sina.com.cn/comment/skin/feedback.html?channel=ly&newsid=186" target="_blank">鍙嶉鎰忚</a>缁欐垜浠?/p></td>
  </tr>
  <tr>
    <td height="14" bgcolor="#76a9db">&nbsp;</td>
  </tr>
</table>
</body>
</html>我通过body = Encoding.UTF8.GetString(Encoding.Default.GetBytes(body));//body邮件正文
结果出现了乱码.请问应该怎样进行解码才能不出现乱码?