slimta: Mail Transfer Library

The slimta suite was created to provide an MTA (Mail Transfer Agent) taking advantage of new technologies and methodologies to scale horizontally in a virtualized environment. Along with that, slimta is designed to work either as a traditional application or as a software library.

  1. MIT License
  2. Terminology
  3. Continuous Integration buildstatus
  4. IRC Channel: #slimta on Freenode.
  5. Blog
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Python Library

The python-slimta project is a Python library offering the building blocks necessary to create a full-featured MTA. Most MTAs must be configured, but an MTA built with python-slimta is coded. An MTA built with python-slimta can incorporate any protocol or policy – custom or built-in. An MTA built with python-slimta can integrate with other Python libraries and take advantage of Python’s great community.

Changed in version 3.0.0: We are now compatible with Python 3.3+! Compatibility with Python 2.6 has been removed to ease the transition. Huge thanks to our contributors for their efforts! See the Change Log for details.

  1. README
  2. Download [Repository]
  3. Bug Reports
  4. Change Log
  5. Installation
  6. API Reference
  7. Python Library Usage
import logging

from slimta.edge.smtp import SmtpEdge
from slimta.queue import Queue
from slimta.queue.dict import DictStorage
from slimta.relay.smtp.mx import MxSmtpRelay
from slimta.policy.headers import *
from slimta.policy.split import RecipientDomainSplit

logging.basicConfig(level=logging.DEBUG)

# Set up outbound delivery by MX lookup.
relay = MxSmtpRelay()

# Set up local queue storage to in-memory dictionaries.
queue_storage = DictStorage({}, {})
queue = Queue(queue_storage, relay)
queue.start()

# Ensure necessary headers are added.
queue.add_policy(AddDateHeader())
queue.add_policy(AddMessageIdHeader())
queue.add_policy(AddReceivedHeader())
queue.add_policy(RecipientDomainSplit())

# Listen for messages on port 25.
edge = SmtpEdge(('127.0.0.1', 25), queue)
edge.start()
try:
    edge.get()
except KeyboardInterrupt:
    print

Traditional Application

The slimta project is a traditional application built on top of the python-slimta library. It allows a more “out-of-the-box” MTA that offers all the useful, built-in features needed for a normal mail system setup.

  1. README
  2. Download [Repository]
  3. Bug Reports
  4. Configuration and Setup Guide
process:
  slimta:
    daemon: false

tls:
  main: &tls_main
    certfile: '/path/to/cert.pem'
    keyfile: '/path/to/key.pem'

edge:
  outbound:
    type: smtp
    queue: outbound
    listener:
      interface: '127.0.0.1'
      port: 587
    tls: *tls_main
    rules: !include rules.yaml

queue:
  outbound:
    type: memory
    relay: outbound
    policies:
      - { type: add_date_header }
      - { type: add_messageid_header }
      - { type: add_received_header }
      - { type: recipient_domain_split }

relay:
  outbound:
    type: mx
    tls: *tls_main