Best Self Hosted Alternatives to Fastmail

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.

Mail-in-a-Box is a turnkey project that turns a fresh Ubuntu server into a complete, working email system with the surrounding services needed for deliverability and day-to-day administration. It aims to make running your own mail service practical by installing and configuring a curated, integrated stack.

Key Features

• SMTP and IMAP mail services with integrated webmail
• Web-based control panel to manage users, aliases, domains, DNS records, and backups
• Automated DNS setup (when used as authoritative DNS) including common deliverability and security records
• Automatic TLS certificate provisioning and renewal for mail and web services
• Built-in spam mitigation (filtering and greylisting) and mail filtering rules support
• Daily health checks and monitoring focused on mail service correctness (ports, DNS, certificates)
• Optional contacts and calendar sync services integration
• RESTful API for control-panel actions

Use Cases

• Hosting email for multiple users across one or more personal or small-organization domains
• Replacing a hosted mail provider while retaining standard IMAP/SMTP compatibility
• Running an “email appliance” on a VPS with automated security and deliverability checks

Limitations and Considerations

• Designed to be minimally configurable; advanced customization and post-install tweaking are intentionally limited
• Email deliverability can still be affected by external provider policies and IP reputation

Mail-in-a-Box is best suited for individuals and small teams that want a straightforward, integrated mail stack with sane defaults and an admin UI. It combines core mail protocols with the operational pieces (DNS, TLS, monitoring, backups) that are typically the hardest parts to get right.

mailcow: dockerized is an integrated mail server suite packaged as a set of Docker containers. It combines core mail components (SMTP/IMAP) with a web-based administration interface to manage domains, mailboxes, and security features.

Key Features

• Containerized stack managed via Docker Compose for reproducible deployments
• SMTP delivery with Postfix and IMAP access via Dovecot
• Webmail and groupware via SOGo
• Built-in spam filtering with Rspamd and antivirus scanning with ClamAV
• ACME/Let’s Encrypt certificate automation for TLS
• Web admin UI for domains, aliases, mailboxes, and access controls (ACL)

Use Cases

• Self-managed mail hosting for individuals, families, and organizations
• All-in-one email platform for small businesses needing webmail and groupware
• Homelab mail server with integrated spam/virus protection and TLS automation

Limitations and Considerations

• Operating a mail server requires careful DNS and deliverability configuration (SPF/DKIM/DMARC, rDNS) and ongoing maintenance
• Resource usage can be higher than minimalist MTAs due to multiple bundled services

mailcow: dockerized provides a cohesive, production-oriented mail stack with a unified management experience. It is well-suited for administrators who want an integrated suite rather than assembling and maintaining separate mail components.

Stalwart Mail Server is an all-in-one mail and collaboration server built to provide a modern, standards-based alternative to assembling multiple separate components. It combines email delivery and storage, groupware protocols, and built-in security controls in a single, scalable service written in Rust.

Key Features

• Multi-protocol email support including SMTP, IMAP4, POP3, and JMAP
• Collaboration protocols including CalDAV, CardDAV, and WebDAV for calendars, contacts, and file storage
• Integrated spam and phishing defenses, including filtering rules, DNS blocklists, greylisting, and a statistical classifier
• Email authentication and transport security features such as DKIM, SPF, DMARC, ARC, MTA-STS, DANE, and TLS reporting
• Flexible backends for storage and search, with support for multiple databases and optional external search engines
• Built-in web-based administration with real-time stats, queue management, reporting views, and log exploration
• Authentication options including LDAP, SQL, and OpenID Connect, plus roles/permissions and ACLs
• Observability via logging/tracing and metrics integrations, with webhook-based event automation

Use Cases

• Replace a traditional MTA + IMAP store + spam filter stack with a single integrated platform
• Run a domain email service with modern clients via JMAP while retaining IMAP/POP3 compatibility
• Provide calendars, contacts, and file sharing for teams using CalDAV/CardDAV/WebDAV

Limitations and Considerations

• Some advanced scaling and backend options can add operational complexity compared to small single-node deployments

Stalwart Mail Server is well-suited for organizations and individuals who want a secure, standards-compliant email and collaboration platform with modern protocols, integrated protection against abuse, and deployment flexibility from small setups to large clustered environments.

Mailu is a simple yet full-featured email server distributed as a set of Docker images. It provides the core protocols needed to run your own mail infrastructure, plus webmail and an administration interface.

Key Features

• SMTP, Submission, IMAP/IMAP+, and optional POP3 support
• Multiple webmail options and a built-in administration UI
• Aliases, domain aliases, custom routing, auto-forward and auto-reply
• Fetched accounts (fetchmail-style) and ManageSieve support
• Per-domain delegation, global admins, announcements, and mailbox quotas
• Security features including enforced TLS, Let’s Encrypt integration, outgoing DKIM, DMARC/SPF, and anti-spoofing options
• Anti-spam features such as greylisting and auto-learning, plus optional antivirus scanning

Use Cases

• Hosting email for personal domains or small organizations with a web-based admin panel
• Running multi-domain mail hosting with delegated per-domain administration
• Deploying a containerized mail stack with DKIM/DMARC/SPF and spam filtering

Limitations and Considerations

• Deliverability depends on correct DNS configuration (SPF, DKIM, DMARC, rDNS) and IP reputation
• Operating a mail server requires ongoing maintenance (TLS, spam rules, storage quotas, and monitoring)

Mailu focuses on providing a complete, containerized mail stack using standard components rather than a full groupware suite. It is designed to be straightforward to deploy and maintain while offering the security and administrative features expected from a modern mail server.

Roundcube is a browser-based, multilingual IMAP webmail client with an application-like user interface. It provides core email client capabilities through the browser and can be extended and themed via a plugin API and skins.

Key Features

• IMAP client functionality with MIME support
• Address book and contact management
• Folder management and message search
• Spell checking
• Plugin API for extending functionality
• Customizable interface with skins/themes
• Supports multiple database backends for application data storage

Use Cases

• Provide webmail access for an organization’s IMAP mailboxes
• Offer a lightweight browser email client for shared hosting or ISPs
• Deploy a customizable webmail front-end integrated with existing mail infrastructure

Limitations and Considerations

• Requires an existing IMAP server; it is not a full mail server (SMTP/IMAP stack)
• The Git repository snapshot may not correspond to a stable release

Roundcube is a mature webmail interface that fits well when you already operate an IMAP-capable mail system and need a user-friendly, extensible web client. Its plugin ecosystem and skinning support make it adaptable to different environments and branding needs.

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.

Mox is a modern, security-focused, all-in-one email server designed to make running email for your own domain straightforward and low-maintenance. It bundles core mail protocols and deliverability tooling into a single application, with an admin UI and strong operational visibility.

Key Features

• SMTP server for receiving, submission, and delivery, with modern extensions
• IMAP4 server (with extensions) for email client access
• Built-in webmail for reading and sending email in the browser
• Deliverability features including SPF, DKIM, and DMARC (including aggregate reports)
• Modern transport security support such as ACME-managed TLS, MTA-STS and DANE, plus TLS reporting
• Reputation and content-based junk filtering, including per-user Bayesian spam learning and throttling of low-reputation senders
• Admin web interface for managing domains, accounts, aliases/lists, and configuration guidance (including DNS record instructions)
• Account autodiscovery support for easier client configuration
• Optional built-in web server and reverse proxy capabilities
• HTTP/JSON API and webhooks for transactional email and inbound/delivery events, plus Prometheus metrics and structured logging

Use Cases

• Hosting email for personal or small-organization domains with a single integrated stack
• Running a transactional mail endpoint with API-driven sending and delivery event callbacks
• Email testing and development using the local-only test mode

Limitations and Considerations

• POP3 is not supported
• Some advanced features (for example JMAP, Sieve, OAuth2 login, and full mailing list management) are listed as roadmap items rather than fully implemented

Mox is a good fit when you want a cohesive mail server that minimizes external dependencies while still supporting a modern email security and deliverability stack. Its integrated approach, admin UI, and operational tooling aim to reduce the ongoing effort typically associated with running mail infrastructure.

Modoboa is an open source mail hosting and management platform that helps you deploy and operate a full email server through a modern web interface. It integrates common mail components (MTA/IMAP, filtering, reputation and policy features) around a central SQL database.

Key Features

• Web-based administration panel for domains, mailboxes, and aliases
• Integrated webmail with a simplified user interface
• Calendar and address book features
• Per-user mail filtering with Sieve and auto-reply messages
• Reputation and deliverability tooling including DNSBL checks and DMARC reporting
• Optional integrations for content filtering/quarantine workflows (for example via Amavis)
• Email traffic statistics and reporting dashboards
• Modular architecture via extensions for adding functionality

Use Cases

• Hosting email for a small business or organization with multiple domains and users
• Replacing third-party email providers while keeping a webmail-based workflow
• Providing managed mail services with admin and migration tooling

Modoboa is a practical choice for teams that want a unified UI to deploy, configure, and manage a standards-based mail stack while keeping control over data and policies.

emailwiz is a Bash-based installer for Debian/Ubuntu that automatically deploys a complete mail server stack comprising Postfix, Dovecot, SpamAssassin, and OpenDKIM, with TLS via Certbot. It configures PAM-based logins and security features like fail2ban.

Key Features

• Automates installation and configuration of Postfix, Dovecot, SpamAssassin, OpenDKIM, and Certbot TLS
• Links Postfix and Dovecot securely with native PAM log-ins
• Includes fail2ban for server security
• Provides guidance and finishing steps for DNS records (MX, SPF, DMARC, DKIM)
• Offers an isolated/self-signed certificate option for private environments
• Targets Debian/Ubuntu as the operating system

Use Cases

• Deploy a standalone mail server for a small business or home lab on Debian/Ubuntu
• Set up DKIM, SPF, DMARC and TLS to improve email deliverability
• Rapid provisioning of a mail server with minimal manual configuration

Limitations and Considerations

• No graphical webmail interface is installed by default; a mail client is expected
• DNS configuration is required (MX, SPF, DMARC, DKIM) for proper deliverability
• An isolated/self-signed certificate mode exists but will not work for public mail delivery
• The project emphasizes UNIX user accounts (no SQL database)

Conclusion

emailwiz provides an automated, script-driven path to a secure, mail-server setup on Debian/Ubuntu, reducing manual configuration and ensuring standard mail components and DKIM/TLS are in place. It is linked from the author’s site and maintained as a Bash script intended for self-hosted deployments. (github.com)

WildDuck is a modern IMAP/POP3 mail server designed for large-scale deployments. It stores all mail data in a sharded and replicated MongoDB backend and runs stateless Node.js instances that can be scaled behind a load balancer.

Key Features

• First-class IMAP and POP3 support for standard mail clients
• MongoDB-backed storage for messages and metadata, designed for sharding and replication
• Stateless architecture for horizontal scaling and high throughput
• REST API to manage accounts, access, filtering features, and server settings
• Unicode-first support for internationalized email addresses and folders
• Built-in account security features such as application-specific passwords, rate limiting, and MFA helpers (TOTP/U2F)
• Optional support for storing a user GPG public key to encrypt stored emails

Use Cases

• Hosting IMAP mailboxes for large organizations with many users and large quotas
• Building an API-driven mail platform where provisioning and operations are automated
• Running a scalable mail storage and access layer alongside separate SMTP components

Limitations and Considerations

• Opinionated design may not fit setups that depend on traditional MTA/IMAP stacks and features like Sieve-based workflows
• Typically used together with additional components (for example, an SMTP server) to form a complete mail system

WildDuck is a strong fit when you need an API-controlled, horizontally scalable IMAP server architecture rather than a classic single-host mail stack. For high-user-count installations, its stateless design and database-backed storage simplify scaling and operations.

SOGo is a fast, scalable groupware (collaboration) server that provides webmail, calendars, and address books through a modern web interface and open protocols. It is designed to sit alongside existing mail infrastructure and give users a unified experience across desktop and mobile clients.

Key Features

• AJAX-based web interface for mail, calendars, and contacts
• Standards-based interoperability with existing systems via IMAP, CalDAV, and CardDAV
• Mobile synchronization support via Microsoft ActiveSync
• Resource sharing, delegation, and permission handling for calendars and address books
• Works with many native clients without requiring plugins (depending on client capabilities)

Use Cases

• Provide a webmail and groupware frontend on top of an existing IMAP mail server
• Replace proprietary groupware with an open-standards collaboration server for organizations
• Offer shared calendars/contacts with permission management for teams and communities

Limitations and Considerations

• Requires integration with external mail services (for example IMAP/SMTP servers) rather than being a complete mail server by itself

SOGo is a strong fit for deployments that prioritize open standards, scalability, and broad client compatibility. It can be used as a central collaboration layer to provide consistent mail, calendar, and contact access across many devices and clients.

iRedMail is a packaged, open-source mail server solution that automates deployment and integration of standard mail components on mainstream Linux and BSD distributions. It combines mail transport, delivery, webmail/groupware and anti-spam/antivirus tooling into a reproducible installer and offers optional commercial admin/enterprise editions for extra features and support. (iredmail.org)

Key Features

• Automated installer that configures Postfix as MTA and Dovecot for IMAP/POP3 delivery, including secure defaults (TLS, modern password hashing). (github.com)
• Pluggable backends: supports OpenLDAP and SQL backends including MySQL/MariaDB and PostgreSQL for account storage and policies. (iredmail.org)
• Webmail and groupware options: Roundcube webmail and SOGo groupware (CalDAV/CardDAV/ActiveSync) can be deployed as part of the stack. (iredmail.org)
• Anti-spam and antivirus integration: built-in support for SpamAssassin/Rspamd-style filtering, ClamAV, SPF/DKIM/DMARC and quarantining workflows. (docs.iredmail.org)
• Optional web admin panels and commercial tiers: free iRedAdmin (basic), paid iRedAdmin‑Pro with extended features and an online demo for evaluation. (iredmail.org)
• Multiple deployment options and tooling: documented for several mainstream distros (Debian, Ubuntu, Red Hat/CentOS/Rocky/AlmaLinux) and an official dockerized edition is available. (github.com)

Use Cases

• Small-to-medium organizations wanting a self-hosted, privacy-focused mail server with modern mail standards and webmail access.
• Service providers or admins migrating legacy Exchange/hosted systems to an integrated open-source mail stack.
• Teams requiring integrated calendar/contacts (CalDAV/CardDAV/ActiveSync) and per-domain administration via a web panel.

Limitations and Considerations

• Backend choice (OpenLDAP or SQL) is selected at install time and is not trivially switchable after installation; migrating backends requires planned data migration. (forum.iredmail.org)
• Some advanced management features (iRedAdmin‑Pro) and enterprise conveniences are paid; community edition covers core mail functionality but lacks Pro panel features out of the box. (iredmail.org)
• Certain components (notably SOGo groupware) increase resource requirements significantly (larger memory/CPU for ActiveSync/large user bases). (docs.iredmail.org)

In summary, iRedMail is a mature, opinionated integration of proven open-source mail components that simplifies deploying a secure, standards-compliant mail server across mainstream Linux/BSD systems while providing paid options for enhanced management and support. (iredmail.org)

SnappyMail is a simple, modern, and lightweight web-based email client. It is a heavily upgraded and security-focused fork of the RainLoop Webmail Community edition, designed for fast UI performance and easy deployment without requiring a database.

Key Features

• IMAP webmail with a responsive, modern interface and dark mode
• Privacy/GDPR-oriented defaults (removes common third-party integrations and tracking-related features)
• Admin panel for server configuration, domains, and security settings
• Optional address book support (can use MySQL/MariaDB for contacts)
• Sieve script support with an advanced editor for server-side mail filtering rules
• Improved encryption capabilities, including stronger PGP support (supports modern key types)
• Security hardening measures such as syslog logging for auth failures and guidance for fail2ban
• Plugin system, including the ability to load plugins as PHAR packages

Use Cases

• Provide webmail access for a self-hosted or managed IMAP email server
• Offer fast, low-overhead webmail for organizations that want privacy-friendly defaults
• Manage mail filtering rules via Sieve without needing a desktop client

Limitations and Considerations

• POP3 support is removed; IMAP is the primary protocol
• Browser support excludes legacy browsers (for example, Internet Explorer and legacy Edge)

SnappyMail fits well when you need a performant, minimal webmail interface with modern security improvements over the original RainLoop codebase. It is particularly suitable for IMAP-centric setups and users who want a streamlined, privacy-conscious webmail experience.

Dovecot is a secure, high-performance IMAP/POP3/LMTP server and mail storage backend designed for reliability, standards compliance and operational scalability. It provides mailbox indexing, flexible authentication backends and a plugin architecture used by large ISPs and hosting providers. (dovecot.org)

Key Features

• High-performance mailbox indexing with support for Maildir and mbox formats and self-optimizing indexes.
• Flexible authentication backends with many passdb/userdb options and integration points for MTAs (Postfix, Exim) for SMTP authentication.
• Standards-compliant IMAP/POP3/LMTP implementation with many protocol workarounds for client interoperability.
• Extensible plugin system: native Lua scripting support and a rich plugin ecosystem (including the Pigeonhole Sieve/ManageSieve project for Sieve-based filtering).
• TLS/SSL support via OpenSSL with configurable cipher suites, certificates and TLS settings.
• Admin-friendly diagnostics, self-healing index behavior and support for clustered filesystems with caveats for some network filesystems.

(dovecot.org)

Use Cases

• Deploying a production-grade IMAP/POP3/LMTP backend for ISPs, telcos and hosting providers requiring high concurrency and scalability.
• Building mail delivery workflows with server-side filtering using the Pigeonhole Sieve implementation and ManageSieve management.
• Integrating authentication and SMTP submission with existing infrastructure (system userdbs, SQL/LDAP backends, or custom Lua-based userdb/passdb).

(pigeonhole.dovecot.org)

Limitations and Considerations

• Some optional features require additional libraries or build-time options (for example, OpenSSL development headers are required for TLS support when compiling from source). (doc.dovecot.org)
• Using certain clustered/network filesystems (notably NFS) may require careful configuration or workarounds due to caching semantics; administrators should consult filesystem-specific guidance. (dovecot.org)

Dovecot is a mature, widely used mail backend focused on security, performance and extensibility. Its plugin architecture (Lua, Pigeonhole) and broad authentication options make it suitable for both small deployments and large-scale mail services.

Nextcloud Mail is the official webmail application for Nextcloud, providing a modern browser-based email client that connects to standard IMAP/SMTP mailboxes. It integrates tightly with other Nextcloud apps to unify email with your personal and team workflows.

Key Features

• Connect multiple IMAP accounts with a unified inbox
• Send mail via SMTP and manage folders/mailboxes (create, rename, delete, subfolders)
• Conversation/thread view for grouped messages
• Integration with Nextcloud apps such as Contacts, Calendar, Files, and Tasks
• Message composition with rich-text editor support
• Optional encryption features including S/MIME support; can also work with browser-based encryption extensions

Use Cases

• Use Nextcloud as a centralized webmail client for personal and work accounts
• Manage email alongside calendars, contacts, files, and tasks in one interface
• Provide a consistent webmail experience for organizations using existing IMAP/SMTP servers

Nextcloud Mail is a strong choice when you want a capable webmail client inside the Nextcloud ecosystem while continuing to use your existing mail server infrastructure.

Cyrus IMAP is a long-running, production-grade server for hosting email along with contacts and calendars. It focuses on security and scalability by keeping mailboxes in server-managed storage and exposing access via standard protocols.

Key Features

• IMAP and JMAP support for mailbox access
• CalDAV and CardDAV support for calendars and contacts
• POP3, NNTP, and WebDAV protocol support (deployment-dependent)
• Mailbox ACLs and quota management for multi-user environments
• Replication and “Murder” aggregation for large and distributed setups
• Flexible server-side mail filtering via Sieve
• Search capabilities (with optional components depending on build)
• Extensive authentication options via Cyrus SASL
• Integrations for antivirus and antispam toolkits
• Deliverability-related support for SPF, DKIM, and DMARC (typically via integration with surrounding mail stack)

Use Cases

• Hosting IMAP/JMAP mailboxes for an organization where users do not need shell access
• Providing CalDAV/CardDAV services for groupware-style deployments
• Building a scalable mail backend for service providers or large enterprises

Limitations and Considerations

• A full email system typically requires integration with an MTA and additional components for webmail, spam filtering, and DKIM signing

Cyrus IMAP is well-suited to administrators who need a robust standards-based messaging platform with strong performance characteristics and operational controls. It is commonly used in demanding environments where scalability, manageability, and protocol support are priorities.

tine is a modular, PHP-based groupware platform that provides integrated collaboration services for organizations. It bundles calendar, contacts, mail, tasks, CRM, time tracking and file management with sync protocols for common clients.

Key Features

• Unified groupware stack: calendar, address book, tasks, email client, CRM, project time tracking and file manager
• Sync protocols: CalDAV, CardDAV, WebDAV and ActiveSync for broad client compatibility
• Authentication and user management with role/permission support and licensing options
• Deployable as OCI/Docker images with support for PHP 8.1–8.3, MySQL/MariaDB and Redis backends
• Modern web UI built with JavaScript and Vue; server-side runs on PHP (php-fpm) behind Nginx or Apache
• Extensible add-on architecture and administrative tooling for operators

Use Cases

• Provide on-premises collaboration for small to medium organizations replacing cloud groupware
• Centralize CRM, email and time tracking for project billing and client management
• Synchronize calendars and contacts across mobile and desktop clients using CalDAV/CardDAV/ActiveSync

Limitations and Considerations

• Official community releases restrict free instances to five user accounts without a licence key
• Production deployments require careful planning for performance, HA and security; operators should be trained
• Some enterprise features and commercial support are available only via paid packages

tine is suitable for organizations that need a self-hosted, full-featured groupware platform with broad client compatibility and an extensible modular architecture. It is designed for administrators who can manage PHP/MySQL-based deployments and prefer on-premise control.

Simple NixOS Mailserver is a set of NixOS modules that helps you declaratively run a complete mail server on NixOS. It aims to provide a reasonably secure, maintainable setup for hosting email domains with a reproducible Nix configuration.

Key Features

• Declarative NixOS configuration for end-to-end mail server deployment
• SMTP service with modern TLS and authentication options
• IMAP mail access for user mailboxes
• Spam filtering integration and common email hygiene features
• Email authentication support (DKIM, DMARC, SPF)
• Optional webmail support depending on chosen configuration
• Designed to fit naturally into NixOS system management and upgrades

Use Cases

• Self-hosting email for a personal domain on NixOS
• Running mail for small organizations that want reproducible infrastructure
• Homelab mail setups with strong control over configuration and updates

Limitations and Considerations

• Intended for NixOS; not a general-purpose mailserver installer for other distributions
• Deliverability depends on DNS correctness and IP reputation, which must be managed externally

Simple NixOS Mailserver is best suited to users who want an opinionated but flexible email stack managed entirely through NixOS. It provides building blocks for a complete mail system while keeping configuration reproducible and auditable.

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.