Japanese email sent from outlook can't be decoded correctly

[duc2019]

Outlook web client will encode japanese email with gbk (or gb18030) but describe the encoding as gb2312, then griddler can't decode the subject and the body correctly (result 500 error or character corruption).
Here is the fix (workaround):
lixiljp@a9f424b#diff-4f4e46d333f0976e1d6d0b687fe2cda190ce489b155337fea17ba6de3840a12d