html邮件中能否直接内嵌二进制图片文件

Question

例如邮件原始信息类似如下This is a multi-part message in MIME format.--=====002_Dragon861367846351_=====
Content-Type: multipart/alternative;
boundary="=====003_Dragon861367846351_====="
--=====003_Dragon861367846351_=====
Content-Type: text/plain;
charset="gb2312"
Content-Transfer-Encoding: base64o6zE47rDo6ENCg0KoaGhoQ0KDQqhoaGhoaGhoaGhoaGhoaGh1sINCsDxo6ENCg0KIKGhoaGhoaGh
oaGhoSAgICAgICAgICC5+dChwcENCiAgICAgICAgICAgICAgICAgICAgICAgU2Vhbi5HdW9AcG54
Y2hpbmEuY29tDQogICAgICAgICAgICAgICAgICAgICAgIDIwMDMtMTEtMTANCg==--=====003_Dragon861367846351_=====
Content-Type: text/html;
charset="gb2312"
Content-Transfer-Encoding: base64
但是，如何实现呢
这个base64码，需要自己编码么