#!/usr/bin/env python3

import os
import sys
import email
import email.policy
import email.generator

try:
    input = sys.argv[1]
except:
    print('no input file', file = sys.stderr)

with open(input, 'rb') as f:
    msg = email.message_from_binary_file(f, policy=email.policy.SMTP)
    gen = email.generator.BytesGenerator(sys.stdout.buffer)
    gen.flatten(msg)