Send Email Attachments with Unicode Filenames in Django

使用 MIMEApplication 並設置 attachment 的 header
不然如果檔名有中文的話
用 Gmail 收到的附件檔名會是 noname

def withdraw_send_email(request, pk):
    withdraw = get_object_or_404(Withdraw, pk=pk)

    email = '[email protected]'
    subject = _(u'Packer 數位發行服務')
    body = render_to_string('dps/email/withdraw_notice.html', {})

    message = EmailMessage(
        subject=subject,
        body=body,
        to=[email, ],
    )
    message.content_subtype = 'html'

    from email.mime.application import MIMEApplication

    # 檔名包含中文的話，要用這種方式 Gmail 收到的附件檔名才不會是 noname
    filename = '%s 結算表.xlsx' % (withdraw.serial_number[:6].encode('utf-8'))
    file_data = withdraw.file.read()
    attach_file = MIMEApplication(file_data, _subtype='vnd.ms-excel')
    attach_file.add_header('Content-Disposition', 'attachment; filename="%s"' % (filename))

    message.attach(attach_file)

    message.send()

    return HttpResponse('OK')

ref:
https://docs.python.org/2/library/email.mime.html