It is useful in many cases due to its flexible configuration and the ability to handle any number of quarantines and modifications sequential and conditional. Storages and whitelists used by quarantines can be managed with the built-in CLI.

Addionally, pyquarantine-milter provides a sanitized, harmless version of the text parts of e-mails as template variable, which can be embedded in e-mail notifications. This makes it easier for users to decide, if a match is a false-positive or not.
It is also possible to use any metavariable as template variable (e.g. storage ID, envelope-from address, ...). This may be used to give your users the ability to release e-mails or whitelist the from-address for example. A webservice then releases the e-mail from the quarantine.

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.

Dependencies

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

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, 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])
List of hosts and network addresses which are considered local. It is used for the condition option local.
loglevel (optional, default: "info")
Set the log level. This option may be overriden by any rule or action object.
Possible values:
- error
- warning
- info
- debug
pretend (optional, default: false)
Pretend actions, for test purposes. This option may be overriden by any rule or action object.
rules
List of rule objects.

Rule

Config options for rule objects:

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

Config options for action objects:

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 metavariable.
metavar (optional)
Prefix for the name of metavariables which are possibly provided by the envfrom, envto or headers condition. Meta variables will be provided if the regular expressions contain named subgroups, see python.re for details.
If not set, no metavariables will be provided.

Whitelist

Config options for whitelist objects:

type
See section Whitelists.

Actions

Available action types:

add_header

Add new header.
Options:

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

del_header

Delete header(s).
Options:

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

mod_header

Modify header(s).
Options:

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.
Options:

action
Action to perform with the disclaimer.
Possible values:
- 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, default: "wrap")
Set the error policy in case the disclaimer cannot be added (e.g. if the html part cannot be parsed).
Possible values:
- 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.
add_html_body (optional, default: false)
Generate a html body with the content of the text body if no html body is present.

store

Store e-mail.
Options:

type
See section Storages.
original (optional, default: false)
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.
metadata (optional, default: false)
Store metadata.
metavar (optional)
Prefix for the metavariable names. If not set, no metavariables will be provided.
The storage provides the following metavariables:
- ID (the storage ID of the e-mail)
- DATAFILE (path to the data file)
- METAFILE (path to the meta file if metadata is set to true)

notify

Send notification.
Options:

type
See section [Notification types](#Notification types).

quarantine

Quarantine e-mail.
Options:

store
Options for e-mail storage, see action store in section Actions.
If the option metadata is not specificall set for this storage, it will be set to true.
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)
Final milter action to perform. If set, no further rules or actions will be processed.
Possible values:
- 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, default: "Message rejected")
Reject message sent to MTA if milter_action is set to reject.
whitelist (optional)
Options for a whitelist, see whitelist in section Conditions.

Storages

Available storage types:

file

File storage.
Options:

directory
Directory used to store e-mails.
metadata (optional, default: false)
Store metadata file.
mode (optional, default: system default)
File mode when new files are created.

Notification types

Available notification types:

email

E-Mail notification.
Options:

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

Available whitelist types:

db

Whitelist stored in database. The table is created automatically if it does not exist yet.
Options:

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.