Backup emails using IMAP

imap_backup.py

"""
Inspired from http://stackp.online.fr/?p=25s

Create a file named "mail_config.py" containing :

HOST = 'mail.gandi.net'
PORT = 993
USER = 'test@mydomain.net'
PASSWORD = '***'

"""

import imaplib
import ssl
import re
import pickle
import time
import datetime
import os

import mail_config

ROOT_DIR = os.path.dirname(os.path.realpath(__file__))

def backup_mails():
    context = ssl.create_default_context()
    with imaplib.IMAP4_SSL(host=mail_config.HOST, port=mail_config.PORT, ssl_context=context) as imap:

        response_login_code, _ = imap.login(
            user=mail_config.USER,
            password=mail_config.PASSWORD
        )
        assert response_login_code == 'OK'

        response_list_code, response_list_message = imap.list()
        assert response_list_code == 'OK'

        folder_names = [
            re.match(r'^\([^\)]*\) "[^"]*" (.*)$', folder_line.decode()).groups()[0]
            for folder_line in response_list_message
        ]
        # You could see weird codes, like '&AOk-', '&AOg-'... See http://forums.4d.com/Code4D/EN/2/1/15512564/
        # Warning : folder_names[i] could be either SomeName (without quotes) or "Some W&AOk-ird Name" (with quotes)

        folders_content = {}
        for folder_name in folder_names:
            response_select_code, _ = imap.select(folder_name)
            assert response_select_code == 'OK'

            response_search_code, response_search_message = imap.search(None, "ALL")
            assert response_search_code == 'OK'

            folders_content[folder_name] = []

            message_ids = response_search_message[0].split()
            for message_id in message_ids:
                response_fetch_code, response_fetch_message = imap.fetch(message_id, "(BODY.PEEK[])")
                assert response_fetch_code == 'OK'

                folders_content[folder_name].append(response_fetch_message)

    timestamp = time.time()
    time_str = datetime.datetime.fromtimestamp(timestamp).strftime('%Y_%m_%d_%H_%M_%S')

    dump_name = '{}-{}-{}.pickle'.format(mail_config.HOST, mail_config.USER, time_str)
    dump_path = os.path.join(ROOT_DIR, dump_name)
    with open(dump_path, 'wb') as file_handle:
        pickle.dump(folders_content, file_handle)


if __name__ == '__main__':
    backup_mails()