Getting started

Mailer is a single static binary that watches one or more IMAP mailboxes and forwards new mail to Telegram or Discord. Everything runs on a host you control.

Requirements

• An IMAP mailbox reachable over TLS (implicit TLS on 993, or STARTTLS on 143).
• Either a bot token (Telegram) or a webhook URL (Discord) for delivery.
• For Gmail or Google Workspace accounts, an OAuth2 client — password login is no longer accepted by Google. See Gmail over OAuth2.

Install

Download a release binary, or build from source:

git clone https://github.com/elysola/mailer
cd mailer
go build -o mailer .

Configure

Copy config.example.yaml to config.yaml and fill in an account and a notifier. Credentials can come from the file, from a separate file, or from environment variables:

accounts:
  - name: inbox
    host: imap.example.com
    port: 993
    username: [email protected]
    password_file: /run/secrets/imap_password   # or ${IMAP_PASSWORD}
    tls: true
    mailbox: INBOX

telegram:
  bot_token_file: /run/secrets/telegram_token
  chat_id: "12345678"

password_file and the ${VAR} form both keep the secret out of the config file, which matters if the file is ever committed or copied.

Verify the connection

Before leaving the daemon running, confirm both sides work:

./mailer test -config ./config.yaml

This logs in, selects the mailbox, and sends one test message to each notifier. A failure here is almost always credentials, a disabled IMAP setting on the provider side, or a wrong port/TLS combination.

Run

./mailer -config ./config.yaml

State — the UID cursor, the Message-ID deduplication set, and the retry queue — lives in a SQLite file (state.db by default) and survives restarts. Deleting it re-announces existing mail, so keep it.

Next steps

• Gmail over OAuth2 — required for Google accounts
• Privacy Policy — what the software handles
• Terms of Service — terms of use