mail_room

mail_room is a configuration based process that will listen for incoming e-mail and execute a delivery method when a new message is received. mail_room supports the following methods for receiving e-mail:

• IMAP
• Microsoft Graph API

Examples of delivery methods include:

• POST to a delivery URL (Postback)
• Queue a job to Sidekiq or Que for later processing (Sidekiq or Que)
• Log the message or open with LetterOpener (Logger or LetterOpener)

Installation

Add this line to your application's Gemfile:

gem 'mail_room'

And then execute:

$ bundle

Or install it yourself as:

$ gem install mail_room

You will also need to install faraday or letter_opener if you use the postback or letter_opener delivery methods, respectively.

Usage

mail_room -c /path/to/config.yml

Note: To ignore missing config file or missing mailboxes key, use -q or --quiet

Configuration

---
:mailboxes:
  -
    :email: "[email protected]"
    :password: "password"
    :name: "inbox"
    :search_command: 'NEW'
    :logger:
      :log_path: /path/to/logfile/for/mailroom
    :delivery_options:
      :delivery_url: "http://localhost:3000/inbox"
      :delivery_token: "abcdefg"
      :content_type: "text/plain"

  -
    :email: "[email protected]"
    :password: "password"
    :name: "inbox"
    :delivery_method: postback
    :delivery_options:
      :delivery_url: "http://localhost:3000/inbox"
      :delivery_token: "abcdefg"
  -
    :email: "[email protected]"
    :password: "password"
    :name: "inbox"
    :delivery_method: logger
    :delivery_options:
      :log_path: "/var/log/user3-email.log"
  -
    :email: "[email protected]"
    :password: "password"
    :name: "inbox"
    :delivery_method: letter_opener
    :delete_after_delivery: true
    :expunge_deleted: true
    :delivery_options:
      :location: "/tmp/user4-email"
  -
    :email: "[email protected]"
    :password: "password"
    :name: "inbox"
    :delivery_method: sidekiq
    :delivery_options:
      :redis_url: redis://localhost:6379
      :worker: EmailReceiverWorker
  -
    :email: "[email protected]"
    :password: "password"
    :name: "inbox"
    :delivery_method: sidekiq
    :delivery_options:
      # When pointing to sentinel, follow this sintax for redis URLs:
      # redis://:<password>@<master-name>/
      :redis_url: redis://:password@my-redis-sentinel/
      :sentinels:
        -
          :host: 127.0.0.1
          :port: 26379
      :worker: EmailReceiverWorker
  -
    :email: "[email protected]"
    :password: "password"
    :name: "inbox"
    :inbox_method: microsoft_graph
    :inbox_options:
      :tenant_id: 12345
      :client_id: ABCDE
      :client_secret: YOUR-SECRET-HERE
      :poll_interval: 60
      :azure_ad_endpoint: https://login.microsoftonline.com
      :graph_endpoint: https://graph.microsoft.com
    :delivery_method: sidekiq
    :delivery_options:
      :redis_url: redis://localhost:6379
      :worker: EmailReceiverWorker
  -
    :email: "[email protected]"
    :password: "password"
    :name: "inbox"
    :delivery_method: postback
    :delivery_options:
      :delivery_url: "http://localhost:3000/inbox"
      :jwt_auth_header: "Mailroom-Api-Request"
      :jwt_issuer: "mailroom"
      :jwt_algorithm: "HS256"
      :jwt_secret_path: "/etc/secrets/mailroom/.mailroom_secret"

Note: If using delete_after_delivery, you also probably want to use expunge_deleted unless you really know what you're doing.

inbox_method

By default, IMAP mode is assumed for reading a mailbox.

IMAP Server Configuration

You can set per-mailbox configuration for the IMAP server's host (default: 'imap.gmail.com'), port (default: 993), ssl (default: true), and start_tls (default: false).

If you want to set additional options for IMAP SSL you can pass a YAML hash to match SSLContext#set_params. If you set verify_mode to :none it'll replace with the appropriate constant.

If you're seeing the error Please log in via your web browser: https://support.google.com/mail/accounts/answer/78754 (Failure), you need to configure your Gmail account to allow less secure apps to access it: https://support.google.com/accounts/answer/6010255.

Microsoft Graph configuration

To use the Microsoft Graph API instead of IMAP to read e-mail, you will need to create an application in Microsoft Entra ID (formerly known as Azure Active Directory). See the Microsoft instructions for more details:

1. Sign in to the Azure portal.
2. Search for and select Microsoft Entra ID.
3. Under Manage, select App registrations > New registration.
4. Enter a Name for your application, such as MailRoom. Users of your app might see this name, and you can change it later.
5. If Supported account types is listed, select the appropriate option.
6. Leave Redirect URI blank. This is not needed.
7. Select Register.
8. Under Manage, select Certificates & secrets.
9. Under Client secrets, select New client secret, and enter a name.
10. Under Expires, select Never, unless you plan on updating the credentials every time it expires.
11. Select Add. Record the secret value in a safe location for use in a later step.
12. Under Manage, select API Permissions > Add a permission. Select Microsoft Graph.
13. Select Application permissions.
14. Under the Mail node, select Mail.ReadWrite, and then select Add permissions.
15. If User.Read is listed in the permission list, you can delete this.
16. Click Grant admin consent for these permissions.

Restrict mailbox access

Note that for MailRoom to work as a service account, this application must have the Mail.ReadWrite to read/write mail in all mailboxes. However, while this appears to be security risk, we can configure an application access policy to limit the mailbox access for this account. Follow these instructions to setup PowerShell and configure this policy.

MailRoom config for Microsoft Graph

In the MailRoom configuration, set inbox_method to microsoft_graph. You will also need:

• The client and tenant ID from the Overview section in the Azure app page
• The client secret created earlier

Fill in inbox_options with these values:

    :inbox_method: microsoft_graph
    :inbox_options:
      :tenant_id: 12345
      :client_id: ABCDE
      :client_secret: YOUR-SECRET-HERE
      :poll_interval: 60

By default, MailRoom will poll for new messages every 60 seconds. poll_interval configures the number of seconds to poll. Setting the value to 0 or under will default to 60 seconds.

Alternative Azure cloud deployments

MailRoom will default to using the standard Azure HTTPS endpoints. To configure MailRoom with Microsoft Cloud for US Government or other national cloud deployments, set the azure_ad_endpoint and graph_endpoint accordingly. For example, for Microsoft Cloud for US Government:

    :inbox_method: microsoft_graph
    :inbox_options:
      :tenant_id: 12345
      :client_id: ABCDE
      :client_secret: YOUR-SECRET-HERE
      :poll_interval: 60
      :azure_ad_endpoint: https://login.microsoftonline.us
      :graph_endpoint: https://graph.microsoft.us

delivery_method

postback

Requires faraday gem be installed.

NOTE: If you're using Ruby >= 2.0, you'll need to use Faraday from >= 0.8.9. Versions before this seem to have some weird behavior with mail_room.

The default delivery method, requires delivery_url and delivery_token in configuration.

You can pass content_type: option to overwrite faraday's default content-type(application/x-www-form-urlencoded) for post requests, we recommend passing text/plain as content-type.

As the postback is essentially using your app as if it were an API endpoint, you may need to disable forgery protection as you would with a JSON API.

sidekiq

Deliver the message by pushing it onto the configured Sidekiq queue to be handled by a custom worker.

Requires redis gem to be installed.

Configured with :delivery_method: sidekiq.

Delivery options:

• redis_url: The Redis server to connect with. Use the same Redis URL that's used to configure Sidekiq. Required, defaults to redis://localhost:6379.
• sentinels: A list of sentinels servers used to provide HA to Redis. (see Sentinel Support) Optional.
• namespace: [DEPRECATED] The Redis namespace Sidekiq works under. Use the same Redis namespace that's used to configure Sidekiq. Optional.
• queue: The Sidekiq queue the job is pushed onto. Make sure Sidekiq actually reads off this queue. Required, defaults to default.
• worker: The worker class that will handle the message. Required.

An example worker implementation looks like this:

class EmailReceiverWorker
  include Sidekiq::Worker

  def perform(message)
    mail = Mail::Message.new(message)

    puts "New mail from #{mail.from.first}: #{mail.subject}"
  end
end

que

Deliver the message by pushing it onto the configured Que queue to be handled by a custom worker.

Requires pg gem to be installed.

Configured with :delivery_method: que.

Delivery options:

• host: The postgresql server host to connect with. Use the database you use with Que. Required, defaults to localhost.
• port: The postgresql server port to connect with. Use the database you use with Que. Required, defaults to 5432.
• database: The postgresql database to use. Use the database you use with Que. Required.
• queue: The Que queue the job is pushed onto. Make sure Que actually reads off this queue. Required, defaults to default.
• job_class: The worker class that will handle the message. Required.
• priority: The priority you want this job to run at. Required, defaults to 100, lowest Que default priority.

An example worker implementation looks like this:

class EmailReceiverJob < Que::Job
  def run(message)
    mail = Mail::Message.new(message)

    puts "New mail from #{mail.from.first}: #{mail.subject}"
  end
end

logger

Configured with :delivery_method: logger.

If the :log_path: delivery option is not provided, defaults to STDOUT

noop

Configured with :delivery_method: noop.

Does nothing, like it says.

letter_opener

Requires letter_opener gem be installed.

Configured with :delivery_method: letter_opener.

Uses Ryan Bates' excellent letter_opener gem.

ActionMailbox in Rails

MailRoom can deliver mail to Rails using the ActionMailbox configuration options for an SMTP relay.

In summary (from the ActionMailbox docs)

1. Configure Rails to use the :relay ingress option:

# config/environments/production.rb
config.action_mailbox.ingress = :relay

2. Generate a strong password (e.g., using SecureRandom or something) and add it to Rails config: using rails credentials:edit under action_mailbox.ingress_password.

And finally, configure MailRoom to use the postback configuration with the options:

:delivery_method: postback
:delivery_options:
  :delivery_url: https://example.com/rails/action_mailbox/relay/inbound_emails
  :username: actionmailbox
  :password: <INGRESS_PASSWORD>

Receiving postback in Rails

If you have a controller that you're sending to, with forgery protection disabled, you can get the raw string of the email using request.body.read.

I would recommend having the mail gem bundled and parse the email using Mail.read_from_string(request.body.read).

Note: If you get the exception (Rack::QueryParser::InvalidParameterError (invalid %-encoding...) it's probably because the content-type is set to Faraday's default, which is HEADERS['content-type'] = 'application/x-www-form-urlencoded'. It can cause Rack to crash due to InvalidParameterError exception. When you send a post with application/x-www-form-urlencoded, Rack will attempt to parse the input and can end up raising an exception, for example if the email that you are forwarding contain %% in its content or headers it will cause Rack to crash with the message above.

idle_timeout

By default, the IDLE command will wait for 29 minutes (in order to keep the server connection happy). If you'd prefer not to wait that long, you can pass idle_timeout in seconds for your mailbox configuration.

Search Command

This setting allows configuration of the IMAP search command sent to the server. This still defaults 'UNSEEN'. You may find that 'NEW' works better for you.

Running in Production

I suggest running with either upstart or init.d. Check out this wiki page for some example scripts for both: https://github.com/tpitale/mail_room/wiki/Init-Scripts-for-Running-mail_room

Arbitration

When running multiple instances of MailRoom against a single mailbox, to try to prevent delivery of the same message multiple times, we can configure Arbitration using Redis.

:mailboxes:
  -
    :email: "[email protected]"
    :password: "password"
    :name: "inbox"
    :delivery_method: postback
    :delivery_options:
      :delivery_url: "http://localhost:3000/inbox"
      :delivery_token: "abcdefg"

    :arbitration_method: redis
    :arbitration_options:
      # The Redis server to connect with. Defaults to redis://localhost:6379.
      :redis_url: redis://redis.example.com:6379
      # [DEPRECATED] The Redis namespace to house the Redis keys under. Optional.
      :namespace: mail_room
  -
    :email: "[email protected]"
    :password: "password"
    :name: "inbox"
    :delivery_method: postback
    :delivery_options:
      :delivery_url: "http://localhost:3000/inbox"
      :delivery_token: "abcdefg"

    :arbitration_method: redis
    :arbitration_options:
      # When pointing to sentinel, follow this sintax for redis URLs:
      # redis://:<password>@<master-name>/
      :redis_url: redis://:password@my-redis-sentinel/
      :sentinels:
        -
          :host: 127.0.0.1
          :port: 26379
      # [DEPRECATED] The Redis namespace to house the Redis keys under. Optional.
      :namespace: mail_room

Note: This will likely never be a perfect system for preventing multiple deliveries of the same message, so I would advise checking the unique message_id if you are running in this situation.

Note: There are other scenarios for preventing duplication of messages at scale that may be more appropriate in your particular setup. One such example is using multiple inboxes in reply-by-email situations. Another is to use labels and configure a different SEARCH command for each instance of MailRoom.

Sentinel Support

Redis Sentinel provides high availability for Redis. Please read their documentation first, before enabling it with mail_room.

To connect to a Sentinel, you need to setup authentication to both sentinels and redis daemons first, and make sure both are binding to a reachable IP address.

In mail_room, when you are connecting to a Sentinel, you have to inform the master-name and the password through redis_url param, following this syntax:

redis://:<password>@<master-name>/

You also have to inform at least one pair of host and port for a sentinel in your cluster. To have a minimum reliable setup, you need at least 3 sentinel nodes and 3 redis servers (1 master, 2 slaves).

Logging

MailRoom will output JSON-formatted logs to give some observability into its operations.

Simply configure a log_path for the logger on any of your mailboxes. By default, nothing will be logged.

If you wish to log to STDOUT or STDERR instead of a file, you can pass :stdout or :stderr, respectively and MailRoom will log there.

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request
6. If accepted, ask for commit rights