Email module is used for email message decode and encode, if the header content is gb2312 encoded for example "中文", by design we would finally have a rfc-2047 encoded header as below:
```
=?eucgb2312_cn?b?1tDOxA==?=
```
the test script is as below:
```
from email import header, charset

h = header.make_header([(str("中文").encode("gb2312"),
                         charset.Charset("gb2312"))])
print(h.encode())
```

My question is why don't we use "gb2312" as the charset in rfc-2047 encoded string, considering the "eucgb2312_cn" is only python awareness.

Thanks

I can't tell tell for sure if this behavior is intentional or not from a quick glance at the code (though like you I wouldn't think it would be).

That's part of the legacy api, at this point.  The new api will just use utf8:

from email.message import EmailMessage

m = EmailMessage()
m['Subject'] = '中文'

print(bytes(m))

results in

b'Subject: =?utf-8?b?5Lit5paH?=\n\n'

The fix, assuming it is correct, would be to add the line:

    'eucgb2312_cn': 'gb2312',

to the CODEC_MAP in email/charset.py, and then specify the internal codec name in your Charset call.  I'm not sure that's right, though...once upon I time I think I understood the logic behind the charset module, but I no longer remember the details.

I'd recommend just using the new API and not the legacy API.

Anything before 3.9 only gets security patches.