SMTP to Telegram

smtp_to_telegram is a small program which listens for SMTP and sends all incoming Email messages to Telegram.

Say you have a software which can send Email notifications via SMTP. You may use smtp_to_telegram as an SMTP server so the notification mail would be sent to the chosen Telegram chats.

Getting started

1. Create a new Telegram bot: https://core.telegram.org/bots#creating-a-new-bot.
2. Open that bot account in the Telegram account which should receive the messages, press /start.
3. Retrieve a chat id with curl https://api.telegram.org/bot<BOT_TOKEN>/getUpdates.
4. Repeat steps 2 and 3 for each Telegram account which should receive the messages.
5. Start a docker container:

docker run \
    --name smtp_to_telegram \
    -e ST_TELEGRAM_CHAT_IDS=<CHAT_ID1>,<CHAT_ID2> \
    -e ST_TELEGRAM_BOT_TOKEN=<BOT_TOKEN> \
    kostyaesmukov/smtp_to_telegram

Assuming that your Email-sending software is running in docker as well, you may use smtp_to_telegram:2525 as the target SMTP address. No TLS or authentication is required.

The default Telegram message format is:

From: {from}\\nTo: {to}\\nSubject: {subject}\\n\\n{body}

A custom format might be specified as well:

docker run \
    --name smtp_to_telegram \
    -e ST_TELEGRAM_CHAT_IDS=<CHAT_ID1>,<CHAT_ID2> \
    -e ST_TELEGRAM_BOT_TOKEN=<BOT_TOKEN> \
    -e ST_TELEGRAM_MESSAGE_TEMPLATE="Subject: {subject}\\n\\n{body}" \
    kostyaesmukov/smtp_to_telegram

To enable HTML or Markdown format parsing:

(Not supported by prebuilt image. See Telegram official document for parse_mode values)

docker run \
    --name smtp_to_telegram \
    -e ST_TELEGRAM_CHAT_IDS=<CHAT_ID1>,<CHAT_ID2> \
    -e ST_TELEGRAM_BOT_TOKEN=<BOT_TOKEN> \
    -e ST_TELEGRAM_API_POSTFIX="&parse_mode=html" \
    -e ST_TELEGRAM_MESSAGE_TEMPLATE="<b>{subject}</b>\\n{from} -> {to}\\n{body}" \
    smtp_to_telegram