邮件解码(100分)

下面是邮件的一般分编码，一些邮件utf-8编码在调用utf8toansi后就可以正常显示，而这封邮件却不行，哪往大侠给指点一下？不胜感激！（php中调用echo iconv("UTF-8", "GBK", base64_decode($str));好像可以正常解码，不知道有无办法调用php的解码，或者php可否做成dll等供delphi调用）
------=_NextPart_000_0041_01C8DB8B.E263D670
Content-Type: text/plain;
charset="utf-8"
Content-Transfer-Encoding: base64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------=_NextPart_000_0041_01C8DB8B.E263D670