开发邮件接收组件的邮件编码问题。

[gxdf123]

我在开发邮件接收组件过程中遇到了这个问题，纯文本的邮件怎样判断邮件内容是从哪里开始的呢？
邮件如下：
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Received: from zfd005 (unknown [218.0.202.228]) by smtp10 (Coremail) with SMTP id wKjADWrANRaBE+1Fsx25FA==.2384S2; Tue, 06 Mar 2007 15:08:50 +0800 (CST)Message-ID: <000501c75fbe$47a96fe0$bc01a8c0@df007>From: "lihuiming" <[e-mail]>To: <[e-mail]>Subject: vaefeaewfwDate: Tue, 6 Mar 2007 15:08:44 +0800
MIME-Version: 1.0
Content-Type: text/plain; charset="gb2312"
Content-Transfer-Encoding: base64
X-Priority: 3
X-MSMail-Priority: Normal
X-Mailer: Microsoft Outlook Express 6.00.2900.3028
X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3028
X-Coremail-Antispam:
1U3Yxn0WfASr-VFAUDIcSsGvfJTw4xvF2IEb7IF0Fy264kE64 k0F24lnxkEFVAIw20F6cxK64vIFxWl6VACY4xI67k04243AwCjxxvEw4WlFcxC0VAYjxAx ZF0Ex2IqxwAv7VC0I7IYx2IY67AKxVWUJVWUGwCF72vE52k0Y41lYx0Ex4A2jsIE14v26r 1j6r4UMxkIecxEwVAFwVW8CwAFF20E14v26r1j6r4UM7kC6x804xWl1IIY67AEw4v_Jr0_ Jr4l5I8CrVACY4xI64kE6c02F40Ex7xfM7k0a2IF6F1Un29KB7ZKAUJUUUUUnxnvy29KBj DU0xZFpf9x07UHSoXUUUUU129KBjDU=dmRmZ2JmaHlqZ3lqdWsscmd3YWVmc2RmZWF3cnl0eWp1a3VtdGdzYXJn

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其实邮件内容就是dmRmZ2JmaHlqZ3lqdWsscmd3YWVmc2RmZWF3cnl0eWp1a3VtdGdzYXJn
可是内容开始的标识怎样找哦？

[gxdf123]

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[bidisty]

=号

[gxdf123]

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