MailToTelegramForwarder - Service

Description

MailToTelegramForwarder is a Python based daemon that will fetch mails from a remote IMAP server and forward them via Telegram API. There's no need for a dedicated mail server and piping Alias to a script; you can use any IMAP capable provider like gmail, outlook, self-hosted, etc. to use this feature. Use of a dedicated IMAP mailbox is strongly recommended.

The bot only sends messages, it does not respond or listen.

Installation

Installation is very easy for Linux with Systemd and only needs to copy and edit some files.

Prerequisites

To run "mailToTelegramForwarder.py" you have to make sure Python (Version 3) and following Python libraries are installed:

$> pip install $module_name or $> apt install python3-$module_name

- configparser
- argparse
- email
- telegram-bot
- imaplib2

For Debian 11.x (Bullseye) these packages have to be installed:

Hint: python3-python-telegram-bot is available since Bullseye.

sudo apt install python3-python-telegram-bot python3-imaplib2

Create dedicated system user

Dedicated user is recommended for security reasons, to restrict access to the minimum.

useradd mail2telegram

Download and place files

wget https://github.com/awalon/MailToTelegramForwarder/archive/master.zip
unzip master.zip

cd MailToTelegramForwarder-master

# "chown" can be skipped, if no dedicated user was created
sudo chown mail2telegram:mail2telegram mailToTelegramForwarder.py
sudo chown mail2telegram:mail2telegram conf/mailToTelegramForwarder.conf

# make script executable
sudo chmod +x mailToTelegramForwarder.py

# create application folder and link executable to default path
sudo mkdir /opt/mailToTelegramForwarder
sudo cp mailToTelegramForwarder.py *.md /opt/mailToTelegramForwarder/
sudo ln -sT /opt/mailToTelegramForwarder/mailToTelegramForwarder.py /usr/local/bin/mailToTelegramForwarder

# create folder for configuration files
sudo mkdir /etc/mail-to-telegram-forwarder
sudo cp conf/mailToTelegramForwarder.conf /etc/mail-to-telegram-forwarder/

You should edit /etc/mail-to-telegram-forwarder/mailToTelegramForwarder.conf now.

sudo vi /etc/mail-to-telegram-forwarder/mailToTelegramForwarder.conf

Command line options

-c, --config: Configuration file.

-o, --read-old-mails (optional): Read mails received before application was started. Can be used to overwrite read_old_mails as defined by configuration file.

Configuration

Mail

At least server, user and password have to be updated for access to your Mail server with IMAP support.

user: On many servers email/username should be in format user@hostname.com.

password: If you had enabled 2-factor authentication on your mail server (or Google Account), you have to create an application password for the bot. Hint: This script does not support 2-factor authentication.

[Mail]
# IMAP server
server: <IMAP mail server>
# IMAP port (default: 993)
#port: <IMAP mail server port like 993>

# IMAP user
user: <mailbox user, ex. my-mail-id>
# IMAP password
password: <mailbox password>

# IMAP connection timout in seconds (default: 60)
#timeout: 60

# use timer in seconds
#refresh: 10

# disconnect after each loop, not recommended for short refresh rates: [True|False]
#disconnect: False

folder [Default 'Inbox']: Can be used to restrict forwarded mail to a predefined folder. Ex.: Mail folder, which contains preprocessed mails by server side ruleset(s).

# IMAP folder on server to check, ex.: INBOX (default)
#folder: <IMAP (sub)folder on server>

search [Default '(UID ${lastUID}:* UNSEEN)']: IMAP search command to filter mails handled by this script. Predefined default will forward all UNSEEN mails since script was started. All these mails will be automatically marked as seen.

Check IMAP specs for further information. Most important search commands:

ALL: All mails

UID: Mails UID on server, which can defined a range of mails UIDs on mail server. Ex.: UID <start>:<end> or UID <start>:*.

UNSEEN: Unseen mails, which will be automatically marked as seen during search.

HEADER <header field> "<search string>": Search mails by header fields like Subject or From. Ex.: HEADER From "@google.com" or HEADER Subject "Some News"

Supported Placeholder for UID value: ${lastUID}: Contains UID of most recent mail on startup and will be updated to UID of last forwarded mail. Is used to process new mails only (since start or last loop).

# Check IMAP specs for more info.
#search: (UID ${lastUID}:* UNSEEN HEADER Subject "<Subject or Part of Subject>")

read_old_mails [Default False]: Read mails received before application was started. See command line option -o or --read-old-mails for one-time use.

max_length [Default 2000]: Email content will be trimmed, if longer than this value. HTML messages will be trimmed to this number of characters after unsupported HTML Elements was removed.

HINT: Content will be trimmed after formatting was applied. Hidden HTML or Markdown elements next to masked characters of Telegram message will be counted too. Expectation: Forwarded content will be smaller than this value.

# max length (characters) of forwarded mail content
#max_length: 2000

ignore_inline_image Ignore embedded image(s) if regular expression matches source attribute.

Example: Remove 1x1 pixel image used for layout based on file name using ignore_inline_image: (spacer\.gif): <img src="http://img.mitarbeiterangebote.de/images/newsletter/spacer.gif"/>

# ignore inline image by regular expression
#ignore_inline_image: (spacer\.gif)

Telegram

bot_token: When the bot is registered via @botfather it will get a unique and long token. Enter this token here (ex.: 123456789:djc28e398e223lkje).

forward_to_chat_id: This script posts messages only to predefined chats, which can be a group or individual chat. The easiest way to get the ID of a chat is to add the @myidbot bot to the chat. After ID bot was started with /start own ID can be requested by /getid (ID > 0), if ID bot was added to a group chat /getgroupid (ID < 0) provides ID of group chat.

Hint: Bot should be added to the chat to be able to post.

[Telegram]
# from @BotFather: Like "<Bot ID:Key>"
bot_token: <Bot Token>
# ID of TG chat or user (<ID>, ex.: 123456) who gets forwarded messages.
forward_to_chat_id: <Chat/User ID>

Optional part of Telegram related configuration:

markdown_version[Default 2]: Can be used to switch between version 1 and 2 of Telegrams markdown, if prefer_html was set to False or mail has no HTML content.

# markdown version: [1|2]
#markdown_version: 2

If prefer_html [Default True] was set to True, script prefers HTML content over plain text part and HTML formatted message will be sent to Telgram:

Hint: Can be used to get clickable links from HTML mails in forwarded Telegram message.

# prefer HTML messages: [True|False]
#prefer_html: True

If both (forward_mail_content and forward_attachment) was set to False only a short summary having From, Subject and names of attached file(s) will be forwarded:

# forward attachments: [True|False]
#forward_mail_content: True
# forward attachments: [True|False]
#forward_attachment: True

Extract embedded image(s), send them before mail content and add placeholders at original position with captions of image:

# forward embedded images: [True|False]
#forward_embedded_images: True

See configuration template conf/mailToTelegramForwarder.conf for further information.

Installing as systemd service

sudo cp systemd/mail-to-telegram-forwarder@.service /etc/systemd/system/
sudo systemctl daemon-reload

Start systemd daemon

Daemon can be started by configuration file, as multiple configurations are supported on a single server.

You may enable and start the daemon, now:

# start service with default configuration
sudo systemctl start mail-to-telegram-forwarder@mailToTelegramForwarder

# check status
sudo systemctl status mail-to-telegram-forwarder@mailToTelegramForwarder

# enable service, to start default configuration on startup
sudo systemctl enable mail-to-telegram-forwarder@mailToTelegramForwarder

# check log messages
sudo journalctl -u mail-to-telegram-forwarder@mailToTelegramForwarder

Update

# remove old package
rm master.zip

# get most recent code from GitHub
wget https://github.com/awalon/MailToTelegramForwarder/archive/master.zip

# use 'A' to replace [A]ll
unzip master.zip
cd MailToTelegramForwarder-master

# "chown" can be skipped, if no dedicated user was created
sudo chown mail2telegram:mail2telegram mailToTelegramForwarder.py
sudo chown mail2telegram:mail2telegram conf/mailToTelegramForwarder.conf

# make script executable
sudo chmod +x mailToTelegramForwarder.py

# copy script to installation folder
sudo cp mailToTelegramForwarder.py *.md /opt/mailToTelegramForwarder/

# compare configruation file and manually update if needed
diff -y conf/mailToTelegramForwarder.conf /etc/mail-to-telegram-forwarder/mailToTelegramForwarder.conf

# restart service
sudo systemctl restart mail-to-telegram-forwarder@mailToTelegramForwarder

# check status
sudo systemctl status mail-to-telegram-forwarder@mailToTelegramForwarder

Authors

• Florian Paul Hoberg - Initial work - @gyptazy
• angelos-se - Fork - @angelos-se based on - Initial work - Luca Weiss @z3ntu [Abandoned]
• Awalon - Merged and enhanced Version - @awalon

License

This project is licensed under the GPLv3 License - see the LICENSE.md file for details, some parts (from IMAPBot) are licensed under the The MIT License (MIT) - see the LICENSE-MIT.md file for details.