Deploying Schleuder

Introduction

Schleuder is an encrypted mailing list manager with features for secure group communication. It enables mailing lists where all traffic is automatically encrypted and can optionally resend messages with the list’s key, providing anonymity and privacy for list members.

Built with security-conscious organizations in mind, Schleuder supports GPG encryption, keyword-based commands, and flexible access control. It’s used by activists, journalists, and organizations that need confidential group communication while maintaining the simplicity of email.

Key highlights of Schleuder:

GPG Encryption: End-to-end encrypted mailing list traffic
Remailer Mode: Forward messages with list’s signature
Keyword Commands: Manage lists via email
Member Management: Add, remove, and manage subscribers
Access Control: Configurable send and admin permissions
Key Management: Automatic key handling and distribution
MIME Support: Handle attachments securely
REST API: Programmatic list management
Web Interface: Optional web-based administration
Integration: Works with standard MTAs

This guide walks through deploying Schleuder on Klutch.sh using Docker, configuring encrypted mailing lists, and managing secure communications.

Why Deploy Schleuder on Klutch.sh

Deploying Schleuder on Klutch.sh provides several advantages for secure communication:

Simplified Deployment: Klutch.sh builds your Schleuder configuration automatically.

Persistent Storage: Attach volumes for keyrings and list data.

HTTPS by Default: Secure access to the web interface.

GitHub Integration: Version control your configuration.

Reliable Delivery: Always-on for consistent email processing.

Prerequisites

Before deploying Schleuder on Klutch.sh, ensure you have:

A Klutch.sh account
A GitHub account with a repository
Basic familiarity with Docker and GPG
SMTP server for sending email
MX records pointing to your deployment
Understanding of GPG key management

Deploying Schleuder on Klutch.sh

Create Your Repository

Create a new GitHub repository for your deployment. Add a Dockerfile:

FROM ruby:3.1-slim

RUN apt-get update && apt-get install -y \
    gnupg \
    build-essential \
    libsqlite3-dev \
    && rm -rf /var/lib/apt/lists/*

RUN gem install schleuder schleuder-web

WORKDIR /var/lib/schleuder

ENV SCHLEUDER_CONFIG=/etc/schleuder/schleuder.yml

EXPOSE 4443

HEALTHCHECK --interval=30s --timeout=10s --start-period=30s --retries=3 \
  CMD curl -fsk https://localhost:4443/status || exit 1

CMD ["schleuder-api-daemon", "-p", "4443"]

Create Configuration

Add schleuder.yml:

lists_dir: /var/lib/schleuder/lists
plugins_dir: /var/lib/schleuder/plugins

api:
  host: 0.0.0.0
  port: 4443

smtp_settings:
  address: smtp.example.com
  port: 587
  domain: example.com
  authentication: plain
  user_name: schleuder@example.com
  password: your_smtp_password
  enable_starttls_auto: true

Push to GitHub

Commit and push your files.

Create a New Project on Klutch.sh

Navigate to the Klutch.sh dashboard and create a new project.

Create a New App

Connect your GitHub repository.

Configure HTTP Traffic

In the deployment settings:

Select HTTP as the traffic type
Set the internal port to 4443

Set Environment Variables

Configure settings:

Variable	Value
`SCHLEUDER_API_KEY`	Secure API key
`SMTP_PASSWORD`	SMTP password

Attach Persistent Volumes

Add volumes:

Mount Path	Recommended Size	Purpose
`/var/lib/schleuder`	10 GB	Lists and keyrings
`/etc/schleuder`	100 MB	Configuration

Deploy Your Application

Click Deploy to build.

List Management

Creating Lists

Create new encrypted lists:

schleuder-cli lists new mylist@example.com admin@example.com

Adding Subscribers

Add members with their public keys:

schleuder-cli subscriptions new mylist@example.com member@example.com --key member.asc

List Configuration

Configure list behavior:

# /var/lib/schleuder/lists/mylist@example.com/list.conf
send_encrypted_only: true
receive_encrypted_only: true
receive_signed_only: true

Email Commands

Keyword Interface

Manage lists via email:

Command	Description
`X-LIST-NAME`	Specify target list
`X-SUBSCRIBE`	Subscribe address
`X-UNSUBSCRIBE`	Remove subscription
`X-LIST-KEYS`	List public keys
`X-ADD-KEY`	Add subscriber key

Example Command Email

To: mylist-request@example.com
Subject: Commands

X-LIST-NAME: mylist@example.com
X-SUBSCRIBE: newmember@example.com

Key Management

List Key

Each list has a GPG keypair:

Generated on list creation
Signs outgoing messages
Decrypts incoming messages

Subscriber Keys

Manage member keys:

# Add key
schleuder-cli subscriptions set-key mylist@example.com member@example.com key.asc

# List keys
schleuder-cli subscriptions list mylist@example.com

Key Distribution

Share list public key:

Include in welcome message
Publish on web
Keyserver upload

Security Features

Encryption Options

Configure encryption requirements:

Option	Description
`send_encrypted_only`	Only send encrypted
`receive_encrypted_only`	Require encrypted input
`receive_signed_only`	Require signatures

Remailer Mode

Enable anonymous forwarding:

resend_encrypted_only: true
include_list_headers: false

Access Control

Restrict sending:

send_admin_only: false
subscribers_only: true

Web Interface

Schleuder Web

Deploy web management:

require 'schleuder-web'
run SchleuderWeb::App

Features

Web interface provides:

List management
Subscriber editing
Key management
Configuration

MTA Integration

Postfix

Configure Postfix integration:

schleuder_destination_recipient_limit = 1

# /etc/postfix/master.cf
schleuder unix - n n - - pipe
  user=schleuder argv=/usr/bin/schleuder work ${recipient}

Transport Maps

Route to Schleuder:

mylist@example.com schleuder:
mylist-request@example.com schleuder:

API Usage

REST API

Programmatic management:

curl -H "Authorization: Bearer API_KEY" \
  https://schleuder.example.com/lists.json

API Operations

Available endpoints:

Lists: create, update, delete
Subscriptions: manage members
Keys: key operations

Troubleshooting

Delivery Issues

Check SMTP configuration
Verify MX records
Review mail logs
Test encryption

Key Problems

Verify key validity
Check key trust
Import missing keys
Update expired keys

API Errors

Verify API key
Check SSL certificates
Review API logs

Additional Resources

Conclusion

Deploying Schleuder on Klutch.sh enables secure, encrypted mailing lists for confidential group communication. With GPG encryption, remailer features, and flexible access control, Schleuder provides the privacy tools needed for sensitive communications. Combined with Klutch.sh’s reliable hosting, you get a trusted platform for secure group email.