Microsoft 365 (Office)

Best Self Hosted Alternatives to Microsoft 365 (Office)

A curated collection of the 15 best self hosted alternatives to Microsoft 365 (Office).

Cloud subscription suite providing hosted Microsoft Office apps (Word, Excel, PowerPoint, Outlook) and related services including Exchange Online, OneDrive, SharePoint, and Teams for document editing, email, file storage, collaboration, and team communication.

Alternatives List

#1
Nextcloud

Nextcloud

Nextcloud is an open-source content collaboration platform providing file sync & share, groupware (calendar, contacts, mail), real-time office editing, chat and video conferencing.

Nextcloud screenshot

Nextcloud is an open-source content collaboration platform that provides file synchronization, sharing, and integrated groupware. It combines file storage, real-time document collaboration, chat/voice/video, calendars and contacts under a single extensible platform.

Key Features

  • File sync & share with web, desktop and mobile clients; WebDAV support for native mounts and third-party clients
  • Real-time collaborative editing with Nextcloud Office (LibreOffice-based online editing)
  • Private communications via Nextcloud Talk: browser and mobile chat, audio/video conferencing, screen sharing and SIP integration
  • Groupware: Calendar (CalDAV), Contacts (CardDAV) and integrated mail features
  • Nextcloud Assistant: integrated/local AI features for summarization, content generation and data-aware queries (platform-integrated)
  • Automation and workflow tools (Flow) plus structured-data app (Nextcloud Tables) and Open Collaboration Services APIs for integrations
  • Storage and backend flexibility: support for object stores (S3-compatible/MinIO/OpenStack Swift), SMB/CIFS, local filesystem and external storage mounts
  • Scalability and performance options: multiple database backends (MySQL/MariaDB/PostgreSQL/SQLite), caching/file-locking with Redis or Memcached, APCu for local cache
  • Extensible apps ecosystem and enterprise add-ons for auditing, access control, compliance and identity integrations

Use Cases

  • Secure enterprise file sync, internal collaboration and compliance-focused deployments for organizations needing data control
  • Education and public-sector deployments requiring granular access control, audit trails and privacy-preserving collaboration
  • Service providers and hosters offering branded/cloud storage and collaboration services built on a customizable platform

Limitations and Considerations

  • Production-scale deployments require careful configuration (database selection, caching, file-locking). SQLite is only suitable for testing or very small installs.
  • Some advanced capabilities (distributed scaling, object-storage primary setups, enterprise-grade support and specific integrations) require additional infrastructure, configuration, or commercial Enterprise services.
  • Performance can degrade if many heavy third-party apps are enabled or if recommended caching (e.g., Redis) is not configured; upgrades and maintenance need planning for large installations.

Nextcloud provides a comprehensive, extensible platform for organizations and individuals who need control over their collaboration stack. It balances a broad feature set with modularity so deployments can be tailored to small setups or large, regulated environments.

33.8kstars
4.7kforks
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#2
Etherpad

Etherpad

Etherpad is a web-based real-time collaborative editor with chat, rich-text formatting, and a plugin framework for customization and integrations.

Etherpad screenshot

Etherpad is a web-based editor that lets multiple people write and edit the same document at the same time. It focuses on fast real-time collaboration and can be extended to fit many workflows via a large plugin ecosystem.

Key Features

  • Real-time collaborative editing with live cursor/author colors
  • Built-in chat alongside the editor for in-context discussion
  • Rich-text editing capabilities (formatting and structured content)
  • Extensible plugin framework to add features and integrations
  • HTTP API for managing pads, users, and groups; includes OpenAPI definition
  • Data export options and embeddable usage for integration into other apps
  • Multi-language interface support

Use Cases

  • Team meeting notes and collaborative drafting sessions
  • Classroom or workshop live note-taking and shared exercises
  • Embedding collaborative editors into existing web applications via API

Limitations and Considerations

  • Advanced functionality (authentication methods, additional editor features, conferencing) often requires installing and maintaining plugins
  • For production deployments, a dedicated database is recommended instead of the default development-oriented storage

Etherpad is a mature choice for organizations that need lightweight, browser-based collaboration with real-time editing. Its API and plugin system make it suitable both as a standalone editor and as a component embedded into larger platforms.

18.1kstars
3kforks
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#3
docker-mailserver

docker-mailserver

Production-ready mail server stack in a Docker container with SMTP, IMAP/POP3, LDAP auth, anti-spam/AV, DKIM/DMARC, and optional OAuth2 support.

docker-mailserver screenshot

docker-mailserver (DMS) is a production-ready, containerized email server appliance that bundles common mail components into a single Docker image. It is designed to be “full stack but simple”, emphasizing file-based configuration (no SQL database) to keep setups easy to version, deploy, and upgrade.

Key Features

  • SMTP server with Postfix
  • IMAP and POP3 server with Dovecot
  • Optional LDAP-backed authentication (including SASL)
  • Anti-spam stack integration (including Rspamd and SpamAssassin options)
  • Antivirus scanning with ClamAV
  • Email authentication protections with DKIM and DMARC support
  • Abuse and brute-force mitigation via Fail2ban and Postscreen
  • TLS certificate support including Let’s Encrypt, as well as manual/self-signed certificates
  • Included maintenance and administration helper script (setup.sh)

Use Cases

  • Self-hosting mail for a personal domain or homelab with a Docker-based workflow
  • Running small-to-medium organization mail services with common anti-spam and security components
  • Providing a reproducible, version-controlled mailserver configuration for teams and environments

Limitations and Considerations

  • Mail hosting requires careful DNS and deliverability configuration (SPF, DKIM, DMARC, rDNS) and ongoing monitoring to avoid delivery issues
  • Advanced customization may require inspecting the running container or using startup patch scripting for overrides

docker-mailserver is a practical option when you want a complete mail stack in a single container while retaining transparent, file-based configuration. It aims to reduce operational complexity without hiding the underlying building blocks that power a standard email system.

17.7kstars
2kforks
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#4
CryptPad

CryptPad

CryptPad is an end-to-end encrypted collaboration suite with real-time editors, file storage, and sharing, designed to keep document contents private from servers and admins.

CryptPad screenshot

CryptPad is a web-based collaboration suite that provides real-time editors and a drive-like workspace with end-to-end encryption. Documents are encrypted in the browser before being stored or shared, reducing server-side access to content.

Key Features

  • End-to-end encrypted editors for collaborative work in real time
  • Multiple app types, including rich text, code, spreadsheets, presentations, forms, kanban, and whiteboards
  • CryptDrive-style file organization with folders and shared documents
  • Link-based sharing to collaborate without requiring recipients to create an account
  • Designed to minimize sensitive data exposure to operators (zero-knowledge-style content storage)

Use Cases

  • Privacy-focused alternative to cloud office suites for teams, schools, and organizations
  • Secure collaboration on meeting notes, project planning boards, and shared spreadsheets
  • Sharing files and documents via links without exposing personal identifiers

Limitations and Considerations

  • While content is encrypted, clients must still trust the server to deliver honest application code (risk of active attacks)
  • Security depends on instance configuration and keeping deployments up to date

CryptPad combines familiar collaboration workflows with strong privacy properties, making it well-suited for groups that need real-time editing without giving a provider access to document contents. It can be used as a full collaboration workspace for documents, boards, and shared files.

7.2kstars
795forks
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#5
ONLYOFFICE Docs

ONLYOFFICE Docs

Self-hostable online office suite for viewing and collaboratively editing documents, spreadsheets, presentations, PDFs, and forms with strong OOXML compatibility.

ONLYOFFICE Docs is a self-hostable collaborative online office suite that provides web-based viewers and editors for text documents, spreadsheets, presentations, forms, and PDFs. It is designed to be integrated into other platforms and supports real-time co-authoring with high compatibility for Office Open XML formats.

Key Features

  • Web-based editors for documents, spreadsheets, presentations, PDF, and forms
  • Real-time collaborative editing with comments and change tracking
  • Document conversion service for common office formats
  • Plugin and macro support for extending editor capabilities
  • Integration options for third-party sync-and-share/DMS platforms via APIs
  • Multi-language interface and localization support

Use Cases

  • Add in-browser document editing to a file sync/share or DMS platform
  • Team collaboration on office documents with review workflows
  • Embed document viewers/editors into custom web applications

Limitations and Considerations

  • Community Edition licensing is AGPLv3; some advanced capabilities are reserved for commercial editions
  • Some security features (such as end-to-end encryption “Private Rooms”) depend on other ONLYOFFICE components rather than Docs alone

ONLYOFFICE Docs fits organizations that need browser-based office editing on their own infrastructure, especially when OOXML compatibility and integrations are key. It can be deployed as a standalone document server or embedded into other products to provide collaborative editing.

6.1kstars
1.2kforks
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#6
Maddy Mail Server

Maddy Mail Server

Go-based, modular mail server implementing SMTP/LMTP/IMAP with built-in DKIM/SPF/DMARC, storage backends (SQLite/Postgres/S3), Prometheus metrics and Docker support.

Maddy Mail Server screenshot

Maddy is a composable, single-daemon mail server written in Go that implements SMTP (MTA), SMTP/LMTP (MX/Submission) and IMAP access. It includes built-in mail security protocols (DKIM, SPF, DMARC, DANE, MTA-STS), ACME certificate handling and OpenMetrics/Prometheus telemetry, aiming to replace multiple traditional components with a unified configuration and low maintenance surface. (maddy.email)

Key Features

  • Integrated mail stack: send and receive mail (MTA/MX) and provide mailbox access (IMAP/LMTP) from one daemon; IMAP storage is explicitly marked as beta. (maddy.email)
  • Built-in security: DKIM signing and verification, SPF checks and DMARC handling plus support for DANE and MTA-STS.
  • Flexible storage: filesystem blob store and S3-compatible blob backend; SQL-indexed IMAP storage supports SQLite, PostgreSQL and CockroachDB. (maddy.email)
  • Observability & ops: OpenMetrics/Prometheus endpoint, ACME-based automatic certificate management, prebuilt tarballs and an official Docker image for deployment. (maddy.email)
  • Integrations and extensions: designed to interoperate with Dovecot, rspamd, Mailman and external SMTP targets; modular pipeline for checks, signing and routing.
  • Developer & build: Go-based codebase using Go modules; release notes document build/tooling requirements for modern Go toolchains. (github.com)

Use Cases

  • Self-hosted mail for individuals or small teams who want an all-in-one MTA+IMAP server with security defaults.
  • Consolidating mail delivery and filtering pipelines to reduce the number of separate services (Postfix/Dovecot/OpenDKIM/etc.) to a single configurable daemon.
  • Containerized or VPS deployments where observability (Prometheus) and S3/backed storage are desirable.

Limitations and Considerations

  • IMAP storage is labelled as "beta" in the project documentation; users requiring mature, feature-rich IMAP implementations are advised to consider pairing maddy with established IMAP servers (e.g., Dovecot) for production IMAP feature parity. (maddy.email)
  • SQLite-based storage has write-locking characteristics and checkpoint/vacuum considerations that can limit parallel write throughput; larger or high-concurrency deployments should use a server-grade RDBMS (Postgres/CockroachDB). (maddy.email)

Maddy provides a compact, security-focused mail server alternative that centralizes mail delivery, storage and protocol handling into a single Go daemon. It is well suited for users who prefer an integrated, modular approach but should be evaluated carefully against workload, IMAP feature needs and storage concurrency requirements.

5.8kstars
306forks
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#7
YunoHost

YunoHost

Open-source Debian-based OS and control panel that simplifies installing, managing and securing web apps, mail and services via a web admin and app catalog.

YunoHost screenshot

YunoHost is a Debian-based operating system and web administration layer that streamlines installing and maintaining server applications. It provides a web admin, a user portal (single sign-on), an app catalog and tooling to manage domains, mail, DNS and backups with minimal manual configuration.

Key Features

  • Central web administration panel for users, domains, apps, services, upgrades and backups.
  • App packaging and catalog (YunoHost packages) for one-click installation of common services (Nextcloud, forums, blogs, etc.).
  • Single sign-on user portal for installed applications and account management.
  • Integrated mail stack and admin helpers (Postfix, Dovecot, mail filtering/antispam tooling) and LDAP-based user management.
  • Automated HTTPS certificate handling and TLS configuration managed by the system.
  • Per-app web server configuration and reverse-proxying with NGINX, PHP-FPM support and app-specific vhosts.
  • System-level tooling for backups, upgrades, service supervision and diagnostics.
  • Lightweight footprints for Raspberry Pi, old hardware or VPS deployments; developer-oriented CLI and API for automation.

Use Cases

  • Host personal cloud, file sync, calendars and contacts for individuals or small groups using packaged apps.
  • Provide a simple mail, web and collaboration suite for small organisations or associations without deep sysadmin expertise.
  • Run community services (forums, wikis, federated social software) with centralized user and domain management.

Limitations and Considerations

  • App packaging quality and maintenance vary: some community-maintained packages may lag or require manual fixes when upstream changes.
  • Compatibility with the very latest Debian releases can lag; the project sometimes needs time to adapt to new Debian stable versions.

YunoHost is focused on usability and openness: it aggregates common server components and automations to lower the barrier to self-hosting while leaving advanced configuration available to experienced administrators. The project is community-driven and designed for small-scale deployments, community projects and enthusiasts.

2.8kstars
333forks
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#8
Nextcloud Office

Nextcloud Office

Self-hosted collaborative office suite for Nextcloud providing real-time editing, high-fidelity rendering and support for DOCX, XLSX, PPTX and ODF formats.

Nextcloud Office screenshot

Nextcloud Office integrates Collabora Online into Nextcloud to provide real-time, high-fidelity editing of documents, spreadsheets, presentations and drawings inside the Nextcloud ecosystem. It preserves layout and formatting across many file formats and enables collaborative workflows including comments, suggestions and anonymous public-link editing.

Key Features

  • Real-time multi-user collaborative editing with per-author highlighting and comments
  • High-fidelity server-side rendering that preserves document layout and formatting
  • Broad file format support (DOC, DOCX, XLS, XLSX, PPT, PPTX, ODF and many import/view formats)
  • Integration with Nextcloud apps (Files, Talk, Tasks, Whiteboard, Text, Tables, Collectives) for seamless workflows
  • Anonymous editing via public shared links and granular share controls
  • AI-powered document generation and diagram generation features (configurable)
  • Federated editing support across Nextcloud instances with version and configuration requirements

Use Cases

  • Teams collaborating on documents, spreadsheets and presentations without relying on third-party cloud services
  • Educational deployments where compatibility with varied Office formats and centralized control are required
  • Organizations needing on-premise office editing with integration into existing Nextcloud workflows and access controls

Limitations and Considerations

  • Requires a separate Collabora Online / COOLWSD service to run alongside Nextcloud; the app itself is only the Nextcloud integration
  • Collabora Online can be resource intensive and typically needs dedicated CPU/RAM for good performance at scale
  • Some enterprise-grade stability, scalability and support features are provided only via commercial Collabora/Nextcloud offerings
  • Federated collaborative editing requires compatible versions and specific configuration (trusted servers and embedding/CSP settings)

Nextcloud Office is suitable for organizations that require on-premise collaborative document editing tightly integrated with their Nextcloud instance. It provides a feature-rich, extensible editor experience while keeping data under server control.

420stars
140forks
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#9
Collabora Online Development Edition (CODE)

Collabora Online Development Edition (CODE)

Collabora Online Development Edition (CODE) provides a self-hosted LibreOffice-based online editor for documents, spreadsheets and presentations for testing or small teams.

Collabora Online Development Edition (CODE) screenshot

Collabora Online Development Edition (CODE) is the development version of Collabora Online, a server that enables viewing and editing office documents in a web browser using the LibreOffice/Collabora Office core. It is intended for testing, home use, and small teams, and is typically updated on a frequent release cadence.

Key Features

  • Browser-based editing and viewing for common office document formats
  • Multi-user collaborative editing with real-time updates
  • Server component (coolwsd) designed to be integrated behind a reverse proxy
  • Native Linux packages available for Debian/Ubuntu (deb) and RPM-based distributions
  • Central configuration via coolwsd.xml and service management via systemd

Use Cases

  • Adding online document editing to an existing collaboration platform
  • Evaluating Collabora Online features and compatibility before production deployment
  • Home or small-team shared editing of office documents in a private environment

Limitations and Considerations

  • Not recommended for production environments compared to Collabora Online supported editions
  • Typically expects TLS certificates by default; many deployments use reverse-proxy TLS termination instead

CODE is a practical way to run and test the Collabora Online stack on your own infrastructure while retaining the core collaborative editing capabilities. For production-grade deployments, consider the supported enterprise offerings and operational guidance.

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#10
Stackspin

Stackspin

Stackspin is an open source platform that bundles common team collaboration apps with single sign-on, centralized user management, backups, and monitoring for admins.

Stackspin screenshot

Stackspin is an open source platform for running a value-aligned work collaboration suite you control. It bundles multiple best-of-breed open source apps behind a single login and provides centralized administration for teams.

Key Features

  • Single sign-on across integrated collaboration apps
  • Centralized user and access management via an admin dashboard
  • One-click installation and lifecycle management of multiple apps as a suite
  • Automated backups and instance monitoring for operations teams
  • Integrations aimed at managed/self-hosted deployments, including hosting provider integration

Use Cases

  • Non-profits and small organizations needing a full collaboration stack with one login
  • Distributed research teams coordinating documents, chat, and file sharing
  • Communities running shared tools (docs, tasks, passwords) with streamlined administration

Limitations and Considerations

  • Available apps and integrations depend on the platform’s supported application catalog and deployment options
  • Some contribution workflows may require contacting the maintainers due to anti-spam restrictions

Stackspin is a good fit when you want a cohesive open source “work suite” rather than deploying and managing each collaboration tool separately. It emphasizes simple admin operations, safer defaults, and a unified user experience across apps.

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#11
Zimbra Collaboration

Zimbra Collaboration

Self-hosted enterprise collaboration suite providing email, webmail, calendaring, contacts, and administration for organizations.

Zimbra Collaboration screenshot

Zimbra Collaboration is an enterprise collaboration and messaging platform that provides email, webmail, calendaring, contacts, and related groupware capabilities. It is commonly deployed by organizations that need an on-prem or private-cloud alternative to hosted suites.

Key Features

  • Full-featured webmail client with conversation views, search, folders, tags, and attachments
  • Calendar and scheduling with shared calendars, resource/room scheduling, and free/busy
  • Contacts with address books, distribution lists, and global address list (directory integration)
  • IMAP/POP/SMTP support for desktop/mobile mail clients
  • Admin console for domain/account provisioning, quotas, policies, and monitoring
  • Built-in anti-spam/anti-virus integration options and mail-flow controls (e.g., policies, routing)
  • Backup/restore and delegation/sharing features (edition-dependent)

Use Cases

  • Replace hosted email/collaboration suites for businesses, schools, and public-sector orgs
  • Provide multi-domain email hosting with centralized administration and policy control
  • Offer webmail + CalDAV/CardDAV-style groupware experience for mixed client environments

Limitations and Considerations

  • Some capabilities (e.g., advanced backup, mobile sync/EAS, HA tooling) may depend on the specific Zimbra edition and installed add-ons
  • Operating and upgrading a full mail stack requires careful DNS/TLS, deliverability, and storage planning

Zimbra is suited to organizations needing a mature, admin-friendly groupware platform with broad client compatibility and a rich web UI. Its modular server components and administrative tooling make it a common choice for enterprise-grade self-managed email and collaboration deployments.

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#12
Citadel

Citadel

Citadel is an open source groupware and messaging server providing email, calendars, contacts, and a web interface with room-based collaboration.

Citadel screenshot

Citadel is an open source groupware and messaging platform that combines email and collaboration services in a single server. It uses a room-based architecture to organize discussions and shared content, and can be accessed via web, desktop/mobile clients, and standard protocols.

Key Features

  • Integrated services: email, calendaring, contacts, notes, and collaborative “rooms”
  • WebCit web interface for end-user access and administration
  • Standards-based access via SMTP, IMAP, and XMPP (Jabber)
  • CalDAV/CardDAV-style calendaring and contact access via WebCit (GroupDAV/Webcal)
  • Built-in SSL/TLS support for encrypted connections
  • Optional text-mode terminal client with a classic BBS-style interface

Use Cases

  • Self-managed mail and groupware server for small organizations or families
  • Team collaboration spaces organized by rooms (projects, departments, communities)
  • Centralized calendars and contacts accessible from compatible clients

Limitations and Considerations

  • Full functionality depends on multiple components (Citadel Server plus WebCit for web UI)
  • Uses Berkeley DB as the primary datastore, which may not fit environments standardized on SQL databases

Citadel is well suited for users who want a single, cohesive server for email and collaboration with multiple access methods. Its room-based model and broad protocol support make it flexible for both personal and group communication workflows.

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#13
WikiSuite

WikiSuite

WikiSuite is an integrated open source suite combining wiki/groupware, chat and conferencing, webmail, search, and infrastructure management for organizations.

WikiSuite screenshot

WikiSuite is a curated and integrated collection of open source applications focused on helping organizations manage knowledge, communications, and infrastructure from a unified solution. It centers on Tiki Wiki CMS Groupware and bundles complementary tools for chat, conferencing, webmail, search, and remote/device administration.

Key Features

  • Knowledge management and intranet features via Tiki Wiki CMS Groupware
  • Real-time communications with XMPP-based chat clients and servers
  • Video conferencing using WebRTC conferencing components
  • Unified webmail through a webmail client component
  • Integrated search capabilities via a dedicated search engine component
  • Device and infrastructure management, including remote device administration
  • Web-based administration panels to configure services without editing config files
  • “Upstream first” approach that contributes improvements back to upstream projects

Use Cases

  • Company intranet for documentation, procedures, and collaborative workspaces
  • Secure internal communications with chat and video meetings
  • Small-to-mid sized organization stack for webmail, search, and IT administration

Limitations and Considerations

  • As a multi-component suite, upgrades and troubleshooting may require coordinating several upstream projects and their dependencies

WikiSuite is best suited to knowledge-centric organizations that want a broad set of integrated capabilities while retaining control over deployment, auditing, and extensibility. It provides a pragmatic way to assemble a full collaboration and admin environment using established FLOSS projects.

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#14
Schleuder

Schleuder

Schleuder is an OpenPGP-enabled mailing list manager that encrypts list mail and supports remailing, allowing subscribers and non-subscribers to exchange secure emails via the list.

Schleuder screenshot

Schleuder is a mailing list manager designed for secure group communication using OpenPGP. It acts as an email gateway for a group, handling encrypted list mail and enabling controlled remailing to recipients outside the list.

Key Features

  • OpenPGP-encrypted mailing list workflows for subscriber group communication
  • Email gateway behavior: accept mail from subscribers and non-subscribers
  • Remailing capabilities to send messages to non-subscribers via the list
  • List administration features for managing subscribers and list behavior

Use Cases

  • Secure internal communications for activist groups, NGOs, and collectives
  • Encrypted mailing lists for teams that must interact with external recipients
  • Privacy-focused discussion lists that require OpenPGP-based message handling

Limitations and Considerations

  • Requires participants to use OpenPGP correctly (key management, verification, client support)
  • Operational complexity is higher than typical plaintext mailing list setups due to encryption workflows

Schleuder is well-suited for groups that want mailing-list simplicity while keeping email content protected with OpenPGP. It provides a practical bridge between encrypted subscriber discussions and optional remailing to external contacts under list control.

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#15
GNU Mailman

GNU Mailman

GNU Mailman is a mailing list manager for email discussion lists and newsletters, with web-based administration, archives, moderation tools, and bounce handling.

GNU Mailman screenshot

GNU Mailman is free software for managing email discussion lists and e-newsletter mailing lists. It provides web-based interfaces for subscribers and list owners, and integrates with common mail server setups.

Key Features

  • Web-based subscriber preferences and list administration
  • Moderation and content filtering for posts and attachments
  • Built-in archiving for mailing lists
  • Digest delivery modes for subscribers
  • Automatic bounce processing and subscription management
  • Spam mitigation features and configurable filters

Use Cases

  • Running community discussion lists for open source projects or clubs
  • Operating announcement and newsletter lists for organizations
  • Hosting internal mailing lists for teams with moderation and archives

Limitations and Considerations

  • Mailman 3 is a suite of components (core, web UI, archiver) and typically requires more integration work than a single all-in-one mail server package

GNU Mailman is a mature, widely used mailing list manager with strong administrative controls and automation around subscription and delivery management. It is well-suited for organizations that need reliable email list operations with web-based self-service and moderation capabilities.

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Why choose an open source alternative?

  • •Data ownership: Keep your data on your own servers
  • •No vendor lock-in: Freedom to switch or modify at any time
  • •Cost savings: Reduce or eliminate subscription fees
  • •Transparency: Audit the code and know exactly what's running