mailrise 1.4.0
An SMTP gateway for Apprise notifications.
License: MIT
Requires Python: >=3.8

.. image:: https://raw.githubusercontent.com/YoRyan/mailrise/main/src/mailrise/asset/mailrise-logo.png
  :alt: Mailrise logo


========
mailrise
========


An SMTP gateway for Apprise notifications.

.. |docker| image:: https://badgen.net/docker/pulls/yoryan/mailrise
  :alt: Docker pulls

.. |commit| image:: https://badgen.net/github/last-commit/yoryan/mailrise/main
  :alt: Last commit

.. |checks| image:: https://badgen.net/github/checks/yoryan/mailrise
  :alt: Checks status

|docker| |commit| |checks|

Description
===========

Mailrise is an SMTP server that converts the emails it receives into
`Apprise <https://github.com/caronc/apprise>`_ notifications.  The intended use
case is as an email relay for a home lab or network. By accepting ordinary
email, Mailrise enables Linux servers, Internet of Things devices, surveillance
systems, and outdated software to gain access to the full suite of 60+
notification services supported by Apprise, from Matrix to Nextcloud to your
desktop or mobile device.

.. image:: https://raw.githubusercontent.com/YoRyan/mailrise/main/src/mailrise/asset/homelab-diagram.png
  :alt: A block diagram demonstrating how Mailrise can accept emails from a
        variety of sources and produce notifications for a variety of services

Just as email brought written messages into the 21st century, Mailrise
brings email notifications into the year 2021 and beyond. Compared to a
conventional SMTP server, it's more secure, too—no more replicating your Gmail
password to each of your Linux boxes!

    "After a few very negative experiences with mail providers and their
    detection of spam accounts in the last year... F––k email. I will never set
    up a mail account for notifications. And with Mailrise I don't have to
    anymore!"

    -- `u/Sarcism <https://www.reddit.com/r/selfhosted/comments/wwx0ue/comment/ilnqhkf/>`_

A Mailrise daemon is configured with a list of Apprise
`configuration files <https://github.com/caronc/apprise/wiki/config_yaml>`_.
Email senders encode the name of the desired configuration file into the
recipient address. Mailrise then constructs the resulting Apprise
notification(s) using the selected configuration.

A minimalist Mailrise configuration, for example, might contain a single Apprise
configuration for Pushover::

    configs:
      pushover:
        urls:
          - pover://[...]

And email senders would be able to select this configuration by using the
recipient address::

    pushover@mailrise.xyz

By appending ``.<type>`` to the username component of the address, it is also
possible to specify one of the four Apprise
`notification types <https://github.com/caronc/apprise/wiki/Development_API#message-types-and-themes>`_,
which, if the service you selected supports it, will change the color of the
icon of the resulting notification::

    discord.failure@mailrise.xyz

Email attachments will also pass through to Apprise if the addressed
notification service(s) support attachments.

Mailrise is the sucessor to
`SMTP Translator <https://github.com/YoRyan/smtp-translator>`_, a previous
project of mine that articulated a similar concept but was designed solely for
Pushover.


Installation
============

As a Docker container
---------------------

An official Docker image is available
`from Docker Hub <https://hub.docker.com/r/yoryan/mailrise>`_. To use it, you
must bind mount a configuration file to ``/etc/mailrise.conf``. This mount must
be a *file*, not a directory, and it cannot override anything else in /etc.

Notes for NAS users
^^^^^^^^^^^^^^^^^^^

Consumer NAS operating systems often conceal Docker's controls behind a GUI that
is opaque and difficult to troubleshoot. There are some known gotchas when using
Mailrise with one:

* Unraid can only passthrough directories, not files, making it impossible to
  bind mount the mailrise.conf file. (While attempting to do so, some users have
  accidentally passed through their entire /etc directory, thereby completely
  breaking Python.) To fix this, `override
  <https://docs.docker.com/compose/compose-file/compose-file-v3/#command>`_ the
  image's default command with something like ``-v /etc/myconfig/mailrise.conf``
  so you can passthrough the ``myconfig`` directory without interfering with the
  rest of the filesystem.
* TrueNAS SCALE runs containers as root by default. This breaks Mailrise, which
  is designed to run as a non-root container for enhanced security. Ensure the
  container is running as user ``999`` and group ``999``.


From PyPI
---------

You can find Mailrise `on PyPI <https://pypi.org/project/mailrise/>`_. The
minimum Python version is 3.8+.

Once installed, you should write a configuration file and then configure Mailrise
to run as a service. Here is the suggested systemd unit file::

    [Unit]
    Description=Mailrise SMTP notification relay
    
    [Service]
    ExecStart=/usr/local/bin/mailrise /etc/mailrise.conf
    
    [Install]
    WantedBy=multi-user.target

From source
-----------

This repository is structured like any other Python package. To install it in
editable mode for development or debugging purposes, use::

    pip install -e .

To build a wheel, use::

    tox -e build

If you are using Visual Studio Code, a
`development container <https://code.visualstudio.com/docs/remote/containers>`_
is included with all the Python tooling necessary for working with Mailrise.

Configuration
=============

The ``mailrise`` program accepts a path to a YAML configuration file that
encapsulates the daemon's entire configuration. The root node of this file should
be a dictionary. Mailrise accepts the following keys (periods denote
sub-dictionaries):

====================================== ========== ==========================================================================
Key                                    Type       Value
====================================== ========== ==========================================================================
configs.<name>                         dictionary ``<name>`` denotes the email address associated with the configuration.
                                                  Senders should address their emails to this address. ``<name>`` can be a
                                                  full email address, such as ``notify@mydomain.com``, or it can be a
                                                  username only, such as ``notify``, in which case the default
                                                  ``mailrise.xyz`` domain will be added (resulting in the full email address
                                                  ``notify@mailrise.xyz``).

                                                  `fnmatch <https://docs.python.org/3/library/fnmatch.html>`_ pattern
                                                  matching tokens are also accepted here, though they are considered special
                                                  characters in YAML and therefore must be enclosed in quoted strings.
                                                  Please also note that the domain component still defaults to
                                                  ``mailrise.xyz``, so to match any username on any domain, use ``*@*``.

                                                  Please note that the period character is reserved for sender flags, so it
                                                  cannot be used in the username component of the address.
                                                  ``bad.address`` is not okay, and neither is ``bad.address@mydomain.com``.

                                                  The dictionary value is the Apprise
                                                  `YAML configuration <https://github.com/caronc/apprise/wiki/config_yaml>`_
                                                  itself, exactly as it would be specified in a standalone file for Apprise.

                                                  In addition to the Apprise configuration, some Mailrise-exclusive options
                                                  can be specified under this key. See the ``mailrise`` options below.
configs.<name>.mailrise.title_template string     The template string used to create notification titles. See "Template
                                                  strings" below.

                                                  Defaults to ``$subject ($from)``.
configs.<name>.mailrise.body_template  string     The template string used to create notification body texts. See "Template
                                                  strings" below.

                                                  Defaults to ``$body``.
configs.<name>.mailrise.body_format    string     Sets the data type for notification body texts. Must be ``text``,
                                                  ``html``, or ``markdown``. Apprise
                                                  `uses <https://github.com/caronc/apprise/wiki/Development_API#notify--send-notifications>`_
                                                  this information to determine whether or not the upstream notification
                                                  service can handle the provided content.

                                                  If not specified here, the data type is inferred from the body part of the
                                                  email message. So if you have your body template set to anything but the
                                                  default value of ``$body``, you might want to set a data type here.
import_code                            string     Allows advanced users to supply their own Python code to replace key
                                                  components of Mailrise. Place the path to the Python source file here.
                                                  See "Custom routers and authenticators" below. Custom routers ignore any
                                                  data in the ``configs`` section, and custom authenticators ignore any
                                                  data in the ``smtp.auth`` section.
listen.host                            string     Specifies the network address to listen on.

                                                  Defaults to all interfaces.
listen.port                            number     Specifies the network port to listen on.

                                                  Defaults to 8025.
tls.mode                               string     Selects the operating mode for TLS encryption. Must be ``off``,
                                                  ``onconnect``, ``starttls``, or ``starttlsrequire``.

                                                  Defaults to off.
tls.certfile                           string     If TLS is enabled, specifies the path to the certificate chain file. This
                                                  file must be unencrypted and in PEM format. For testing purposes, you can
                                                  use the ``openssl`` command to
                                                  `create <https://aiosmtpd.readthedocs.io/en/latest/smtp.html#enabling-starttls>`_
                                                  a self-signed certificate.
tls.keyfile                            string     If TLS is enabled, specifies the path to the key file. This file must be
                                                  unencrypted and in PEM format. For testing purposes, you can use the
                                                  ``openssl`` command to
                                                  `create <https://aiosmtpd.readthedocs.io/en/latest/smtp.html#enabling-starttls>`_
                                                  a self-signed certificate.
smtp.auth.basic                        dictionary Enables basic authentication with a static username and password list.
                                                  Each entry in the dictionary represents a valid login. The key is the
                                                  username, while the value is the password.

                                                  Note that credentials will be sent over plaintext unless some form of TLS
                                                  is enabled.
smtp.hostname                          string     Specifies the hostname used when responding to the EHLO command.

                                                  Defaults to the system FQDN.
====================================== ========== ==========================================================================

.. _template-strings:

Template strings
----------------

You can use Python's `template strings
<https://docs.python.org/3/library/string.html#template-strings>`_ to specify
custom templates that Mailrise will construct your notifications from. Templates
make use of variables that communicate information about the email message. Use
dollar signs (``$``) to insert variables.

The following variables are available for both title and body templates:

========== ====================================================================================
Identifier Value
========== ====================================================================================
subject    The email subject.
from       The sender's full address.
body       The full contents of the email body.
to         The full email address of the selected Apprise configuration.
config     The name of the selected Apprise configuration, unless it uses a custom domain, in
           which case this is equivalent to the "to" variable.
type       The class of Apprise notification. This is "info", "success", "warning", or
           "failure".
========== ====================================================================================

Sample file
-----------

If you are new to YAML syntax, you may find the `Online YAML Parser
<https://yaml-online-parser.appspot.com/>`_, which converts YAML syntax to the
underlying JSON structure, a useful aid.

.. code-block:: yaml

    configs:

      # You can send to this config with "basic_assistant@mailrise.xyz".
      #
      # The "-" is *very* important, even when configuring just a single URL.
      # Apprise requires urls to be a YAML *list*.
      #
      basic_assistant:
        urls:
          - hasio://HOST/ACCESS_TOKEN

      # You can send to this config with "telegram_and_discord@mailrise.xyz".
      #
      telegram_and_discord:
        urls:
          - tgram://MY_BOT_TOKEN
          - discord://WEBHOOK_ID/WEBHOOK_TOKEN
        # You can also control the layout of the message with custom template
        # strings.
        mailrise:
          title_template: "Urgent: ${body}"
          body_template: ""
          body_format: text

      # You can send to this config with "my_cool_name@mycooldomain.com".
      #
      my_cool_name@mycooldomain.com:
        urls:
          - pover://USER_KEY@TOKEN

      # We also support wildcards with the fnmatch library; see
      # https://docs.python.org/3/library/fnmatch.html for the full syntax.
      #
      # YAML requires characters like "*" and "[" to be enclosed in quoted
      # strings.
      #
      # This pattern matches addresses like "awesomeperson@mycooldomain.com"
      # and "awesomemail@mycooldomain.com".
      #
      "awesome*@mycooldomain.com":
        urls:
          - pover://USER_KEY@TOKEN

      # Of course, it's also possible to pattern match by the domain.
      #
      "my_cool_name@*.net":
        urls:
          - pover://USER_KEY@TOKEN

      # Wildcard targets are evaluated in the order they appear in the
      # configuration file, and Mailrise uses the first match. So, this config
      # will catch any addresses not matched by the previous targets.
      #
      # Note that if you use "*" as your pattern, Mailrise will expand that to
      # "*@mailrise.xyz", which is probably not the catch-all target you wanted.
      #
      "*@*":
        urls:
          - discord://WEBHOOK_ID/WEBHOOK_TOKEN
          # You can also insert environment variables, a feature lifted directly
          # from Home Assistant. This is useful for reading secrets from
          # container orchestrators like Kubernetes.
          - !env_var MY_SECRET_URL

    # Finally, you can enable TLS encryption and/or SMTP authentication if you
    # want them.

    tls:
      mode: starttls
      certfile: /path/to/certificate.pem
      keyfile: /path/to/privatekey.pem

    smtp:
      auth:
        basic:
          username: password
          AzureDiamond: hunter2

Easy TLS with Traefik
---------------------

Given the popularity of Let's Encrypt, it can be a pain to get Mailrise to work
with automatic certificate renewals. For easy TLS setup, I recommend running
Mailrise in plaintext mode while using a fully-featured ACME client like Traefik
to handle encryption for you.

docker-compose.yml:

.. code-block:: yaml

    mailrise:
      image: yoryan/mailrise
      container_name: mailrise
      restart: unless-stopped
      volumes:
        - ./mailrise.conf:/etc/mailrise.conf:ro
      labels:
        traefik.tcp.routers.mailrise.rule: "HostSNI(`*`)"
        traefik.tcp.routers.mailrise.tls: "true"
        traefik.tcp.routers.mailrise.tls.certresolver: "letsencrypt"
        traefik.tcp.routers.mailrise.tls.domains[0].main: "my.public.mailrise.domain.com"
        traefik.tcp.routers.mailrise.tls.domains[0].sans: ""
        traefik.tcp.routers.mailrise.entrypoints: "mailsecure"

traefik.yml:

.. code-block:: yaml

    entryPoints:
      mailsecure:
        address: ":465"

    certificatesResolvers:
      letsencrypt:
        # ...

SMTP clients can then connect to my.public.mailrise.domain.com, on port 465,
using the TLS-on-connect mode.

Custom routers and authenticators
---------------------------------

If you are handy with Python and want to overcome the limitations of the
configuration format, you can replace Mailrise's notification
routing and SMTP authentication logic with your own. Use the ``import_code``
directive in your configuration file with the path to a Python source file.

The router class, if provided, should be stored in a module-level variable named
``router``. The authenticator callback, if provided, should be stored in a
module-level variable named ``authenticator``.

For further details, refer to the
`sample file used for testing
<https://github.com/YoRyan/mailrise/blob/main/tests/noop_pluggable.py>`_, the
`Mailrise router API
<https://github.com/YoRyan/mailrise/blob/main/src/mailrise/router.py>`_, and
the `aiosmtpd authenticator callback
<https://aiosmtpd.readthedocs.io/en/latest/auth.html#authenticator-callback>`_.