没有主要标头的情况下如何从电子邮件中获取有效载荷并发送未修改的有效载荷

Question

我需要将收件箱a@example.com中的电子邮件重新发送到b@example.org。创建新电子邮件时，是否可以发送有效载荷而不对其进行解码和编码？无论是文本，HTML还是附件。您只需要从另一个邮箱发送原始信件，而无需转发通知。

mail = imaplib.IMAP4_SSL(server)
mail.login(login, password)
mail.list()
mail.select("inbox")

result, data = mail.search(None, "UNSEEN")
if result == 'OK':
    for num in data[0].split():
        result, data = mail.fetch(num, "(RFC822)")
        raw_email = data[0][1]
        try:
            oldmsg = email.message_from_string(raw_email)
        except TypeError:
            oldmsg = email.message_from_bytes(raw_email)
        newmsg = email.mime.multipart.MIMEMultipart(boundary="----")
        newmsg['Subject'] = decode_mime_words(oldmsg['Subject'])
        newmsg['From'] = login
        newmsg['Date'] = strftime("%a, %d %b %Y %H:%M:%S %z")
        newmsg['User-Agent'] = "Roundcube Webmail"
        newmsg['To'] = to
        #part = MIMEBase('application', 'octet-stream')
        if oldmsg.is_multipart():
            for oldpayload in oldmsg.get_payload():
                print(oldpayload.get_payload())
                print("-_________________-")
        else:
            print(oldmsg.get_payload())

            # get attachments
        for part in oldmsg.walk():
            if part.get_content_maintype() == 'multipart':
                continue
            if part.get('Content-Disposition') is None:
                continue
            fileName = part.get_filename()
            if (fileName[:11] == '=?koi8-r?B?') or (fileName[:11] == '=?KOI8-R?B?'):
                fileName = base64.b64decode(fileName[11:]).decode(
                    'KOI8-R')
            elif (fileName[:10] == '=?utf-8?B?') or (fileName[:10] == '=?UTF-8?B?'):
                fileName = base64.b64decode(fileName[10:])
                fileName = fileName.decode('utf-8')

            # name attachemnts
            if bool(fileName):
                filePath = os.path.join('attach', fileName)
                if not os.path.isfile(filePath):
                    fp = open(filePath, 'wb')
                    fp.write(part.get_payload(decode=True))
                    part = MIMEApplication(open(filePath, 'rb').read())
                    part.add_header('Content-Disposition', 'attachment', filename=fileName)
                    newmsg.attach(part)
                    fp.close()