pyquarantine-milter

A pymilter based sendmail/postfix pre-queue filter with the ability to quarantine e-mails, send notifications and modify e-mail headers and/or bodies.
The project is currently in beta status, but it is already used in a productive enterprise environment that processes about a million e-mails per month.

It is useful in many cases due to its flexible configuration and the ability to handle any number of quarantines and/or modifications sequential and conditional.

Dependencies

pyquarantine is depending on these python packages, they are installed automatically if you are working with pip.

• jsonschema
• pymilter
• netaddr
• peewee
• BeautifulSoup

Installation

# Install pyquarantine with pip.
pip install pyquarantine

# Copy the example config file and modify it according to your needs.
cp /etc/pyquarantine/pyquarantine.conf.example /etc/pyquarantine/pyquarantine.conf

# Check the validity of the config file.
pyquarantine-milter -t

Configuration

pyquarantine uses a config file in JSON format. It has to be JSON valid with the exception of allowed comment lines starting with #.

The basic idea is to configure rules that contain actions. Both rules and actions may have conditions. An example of using rules is separating incoming and outgoing e-mails using the local condition. Rules and actions are always processed in the given order.

Global

Global config options:

• socket (optional)
  Socket used to communicate with the MTA. If it is not specified in the config, it has to be set as command line option.

• local_addrs (optional)
  List of hosts and network addresses which are considered local. It is used for the condition option local.
  Default: [fe80::/64, ::1/128, 127.0.0.0/8, 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16]

• loglevel (optional)
  Set the log level. This option may be overriden by any rule or action object. Possible values are:

  • error
  • warning
  • info
  • debug

  Default: info

• pretend (optional)
  Pretend actions, for test purposes. This option may be overriden by any rule or action object.
  Default: false

• rules
  List of rule objects.

Rule

Rule config options:

• name
  Name of the rule.
• actions
  List of action objects.
• conditions (optional)
  See section Conditions.
• loglevel (optional)
  See section Global.
• pretend (optional)
  See section Global.

Action

Action config options:

• name
  Name of the action.
• type
  See section Actions.
• options
  Options depending on the action type, see section Actions.
• conditions (optional)
  See section Conditions.
• loglevel (optional)
  See section Global.
• pretend (optional)
  See section Global.

Conditions

Config options for conditions objects:

• local (optional)
  Matches outgoing e-mails (sender address matches local_addrs) if set to true or matches incoming e-mails if set to false.
• hosts (optional)
  Matches e-mails originating from the given list of hosts and network addresses.
• envfrom (optional)
  Matches e-mails for which the envelope-from address matches the given regular expression.
• envto (optional)
  Matches e-mails for which all envelope-to addresses match the given regular expression.
• headers (optional)
  Matches e-mails for which all regular expressions in the given list are matching at least one e-mail header.
• whitelist (optional)
  Matches e-mails for which the whitelist has no entry for the envelope-from and envelope-to address combination, see section Whitelist.
• var (optional)
  Matches e-mails for which a previous action or condition has set the given meta variable.
• metavar (optional)
  Prefix for the name of meta variables which are provided by the envfrom, envto and headers condition. If not set, no meta variables will be provided.

Whitelist

Config options for whitelist objects:

• type
  See section Whitelists.

Actions

The following action types and options are available.

• add_header
  Add new header.

  • field
    Name of the header.
  • value
    Value of the header.

• del_header
  Delete header(s).

  • field
    Regular expression to match against header names.
  • value (optional) Regular expression to match against the headers value.

• mod_header
  Modify header(s).

  • field
    Regular expression to match against header names.
  • search (optional)
    Regular expression to match against header values. You may use subgroups or named subgroups (python syntax) to include parts of the original value in the new value.
  • value
    New value of the header.

• add_disclaimer
  Append or prepend disclaimer to text and/or html body parts.

  • action
    Action to perform with the disclaimer. Possible values are:

    • append
    • prepend

  • html_template
    Path to a file which contains the html representation of the disclaimer.

  • text_template
    Path to a file which contains the text representation of the disclaimer.

  • error_policy (optional)
    Set the error policy in case the disclaimer cannot be added (e.g. if the html part cannot be parsed). Possible values are:

    • wrap
      A new e-mail body is generated with the disclaimer as body and the original e-mail attached.
    • ignore
      Ignore the error and do nothing.
    • reject
      Reject the e-mail.

    Default: wrap

  • add_html_body (optional)
    Generate a html body with the content of the text body if no html body is present. Default: false

• store
  Store e-mail.

  • type
    See section Storages.
  • original (optional)
    If set to true, store the message as received by the MTA instead of storing the current state of the message, that may was modified already by other actions. Default: false
  • metadata (optional)
    Store metadata. Default: false
  • metavar (optional) If set, some information (e.g. storage id) is saved as meta variables for later use.

• notify
  Send notification to receiver.

  • type
    See section Notifications.

• quarantine
  Quarantine e-mail.

  • store
    Options for e-mail storage, see action store in section Actions.
  • smtp_host
    SMTP host used to release e-mails from quarantine.
  • smtp_port
    SMTP port used to release e-mails from quarantine.
  • notify (optional)
    Options for e-mail notifications, see action notify in section Actions.
  • milter_action (optional)
    Milter action to perform. Possible values are:
    • ACCEPT (Tell MTA to accept the e-mail, skip following rules/actions.)
    • REJECT (Tell MTA to reject the e-mail.)
    • DISCARD (Tell MTA to discard the e-mail.)
  • reject_reason (optional)
    Reject message used if milter_action is set to reject. Default: Message rejected
  • whitelist (optional)
    Options for a whitelist, see whitelist in section Conditions.

Storages

The following storage types are and options are available:

• file
  • directory
    Directory used to store e-mails.
  • metadata (optional)
    Store metadata file. Default: false
  • mode (optional)
    File mode when new files are created. Default: mode set by the system

Notifications

The following notification types and options are available:

• email
  • smtp_host
    SMTP host used to send notifications.
  • smtp_port
    SMTP port used to send notifications.
  • envelope_from
    Envelope-From address.
  • from_header
    Value of the From header.
  • subject
    Subject of the notification.
  • template
    Notification template.
  • repl_img (optional)
    Replacement image used to replace all images in the e-mail body.
  • embed_imgs (optional)
    List of images to embed into the notification e-mail.

Whitelists

The following whitelist types and options are available.

• db
  Whitelist stored in database. The table is created automatically if it does not exist yet.
  • connection
    Database connection string, see Peewee Playhouse Extension.
  • table
    Database table to use.

Developer information

Everyone who wants to improve or extend this project is very welcome.