SOGo adds shared calendars, address books, and a modern webmail interface to your existing Dovecot, Postfix, or Cyrus mail setup, turning familiar infrastructure into a full Exchange competitor. Rather than replacing your IMAP and SMTP servers, SOGo layers collaboration on top of them, becoming the missing link between raw mail delivery and what users actually expect from a workplace communication platform. The ActiveSync implementation synchronizes email, contacts, calendars, and tasks natively with iPhones, Android devices, and Windows without requiring users to manually configure CalDAV endpoints. CalDAV and CardDAV compliance ensures Apple Calendar, Thunderbird (via the official SOGo Connector extension), GNOME Evolution, and Android via DAVx5 all connect without plugins or workarounds. The web interface uses AngularJS Material design with responsive layouts, offering folder management, drag-and-drop calendar scheduling, contact groups, resource booking, and delegation. Shared calendars support free-busy lookups, iMIP event invitations, and per-user ACL permissions for fine-grained access across organizational units. Built on Objective-C with the GNUstep foundation, SOGo delivers exceptional performance: hundreds of concurrent ActiveSync connections from mobile devices alongside webmail and calendar traffic with sub-second response times. With 2,095+ stars and 116 releases, the project has proven its stability in production environments supporting thousands of users. The Docker deployment runs alongside PostgreSQL and memcached.

GroupOffice checks your whole company in at one address: mail, meetings, projects, invoices, and files behind a single login on your own server. The built-in mail client saves messages straight onto projects or contacts, signs and encrypts with S/MIME, and shares folders and accounts across the team. Shared calendars offer team views, bookable resources, and video meetings, while address books carry custom fields and comments so customer knowledge survives staff changes. Projects gather their tasks, files, and discussions in one place, track hours as work happens, and turn those hours and costs into invoices and reports. Support tickets arrive from your website or by email and stay organized by team, and newsletters compose campaigns from templates filled with your own data. Files co-edit in the browser through OnlyOffice or Collabora, connect to desktops over WebDAV, and sync to native phone and computer apps over open protocols. Two-factor authentication, encryption, and a module system you can extend with your own tools keep the office private and shaped to how you actually work. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. AGPL-3.0 licensed.

Mail for your own domain stays on your own server with mailez, a self-hosted stack that delivers over SMTP, IMAP, and POP3 and adds a webmail, calendar, contacts, file storage, and an admin console, all started with a single command. Readers get a draggable three-pane webmail that updates itself over a push channel, merges replies into conversations, folds quoted history, and searches with from:, to:, has:attachment, and date terms. Keyboard shortcuts, a command palette, snooze, scheduled send, undo for bulk moves, and quick reply keep daily mail fast, and the interface installs as an offline-capable app with light and dark themes. Privacy-minded users add PGP signing and encryption, two-factor login, and remote-image blocking, and write server-side rules in a Sieve editor. Calendar, contacts, and Drive sit beside mail, with ICS subscriptions, vCard import, CardDAV and CalDAV sync, and share links. Phones and desktop clients configure themselves through autoconfig. Administrators manage domains, mailboxes, aliases, relays, and external mailbox fetching in one console, generate DKIM keys with a click, and follow a DNS wizard and a health page that verify MX, SPF, DMARC, DKIM, blocklists, and MTA-STS. Audit logs and role-based access keep shared servers accountable. The free community edition runs on a single node, while archiving, DLP, LDAP, ActiveSync, and AI features belong to the paid enterprise edition. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. AGPL-3.0 licensed.

A budget model, the launch document that explains it, and the slides that present it can live side by side in one self-hosted office workspace that people and AI agents edit together. Personal and Team Spaces organize Sheets, Docs, Slides, relational Bases, and Boards, with Recent, Trash, file import, and export views keeping everyday housekeeping close at hand. Sharing follows role and node aware access control, including anonymous viewing, so a single table or document can be opened to a reader without exposing the whole space. Data and references stay connected across artifacts as the workspace changes, which keeps a figure corrected in a sheet consistent with the document that quotes it. The Workspace Agent drafts and revises content in isolated Worktrees, verifies its own changes, and hands the result to a person for review before anything reaches the trunk. Several review rounds can happen while humans keep editing in the Browser, and nothing merges until someone approves it. The Workspace CLI connects existing agents to your deployment, so automation can create content, inspect data, render screenshots and PDFs, and run layout checks before review. Sign-in accepts passwords, GitHub, Discord, or application OAuth, and files move in and out as XLSX, DOCX, PPTX, and CSV without a separate conversion project. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. Apache-2.0 licensed.

Dobase replaces the scattered pile of team subscriptions with one self-hosted workspace where mail, kanban boards, documents, chat, to-do lists, files, a calendar, and video rooms live side by side. Install only the tools your team needs, and share each one with exactly the collaborators you choose; a board for the whole company and a private todo list can sit in the same window. Several people can type in the same document at once, watching each other's colored cursors while the text merges cleanly, and presence faces in the sidebar show who is inside every tool right now. Open tools arrange themselves as tiles in a wide window, so chat can sit next to the board it discusses and the calendar under the mail you are answering. Pressing Cmd+K searches cards, todos, documents, files, chat, events, and mail in one motion, and nearly everything also works from the keyboard alone. Mail threads conversations and lets you accept calendar invites from the message, files get public links guarded by a password and an expiry, and the calendar syncs with CalDAV services or runs on its own. Video rooms with screen sharing join the same workspace, mentions and notifications follow you, and an email digest catches up anyone who was away. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.

End-to-end encrypted by design, CryptPad is a real-time office suite where teams write documents, plan on kanban boards, collect answers with forms, and draw diagrams without the hosting server ever seeing their content. Rich text pages come with comments, replies, @mentions, and a document outline, while the Markdown editor adds a live preview, Mermaid diagrams, mind maps, and math. Kanban columns hold colored, tagged cards with Markdown bodies, and the diagram editor exports PNG, JPG, SVG, or PDF. Optional ONLYOFFICE editors add spreadsheets, word-processing documents, and presentations that several people can edit together. The form builder offers text, choice, grid, date, ranking, and poll questions, conditional sections, and separate author, auditor, and participant roles. Documents can be shared with contacts or teams, by link, or as embed code, with view, edit, present, or view-once access. Passwords, expiry dates, owner lists, and access lists limit who gets in, and every edit lands in a history you can step through, restore, or pin as a named snapshot. CryptDrive keeps files in folders, tags, templates, and a trash bin, while teams get their own drive, chat, and member roles. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. AGPL-3.0 licensed.

Google Workspace and Microsoft 365, replaced by a platform you actually control: Nextcloud is the self-hosted digital workspace. Files is the core: file storage and sync across desktop, mobile, and web clients, with sharing, versioning, and collaboration built in. Around it, Talk provides private text chat, audio/video conferencing with screen sharing, SIP integration, and persistent voice rooms; Groupware bundles calendar, contacts, and mail with delegation support; and Office offers two collaborative suites - the Collabora-based option with deep ODF support, and Euro-Office, whose local-processing architecture delivers strong Microsoft Office compatibility and fast browser rendering with reduced server load. The Nextcloud Assistant threads AI through the platform via a context-aware sidebar, Whiteboard covers visual collaboration, Flow handles automation, and an app ecosystem of hundreds of extensions adds everything from Kanban boards to end-to-end encryption. Hub 26 brings a lighter UI with a unified app switcher and Nextcloud Governance for organizations under strict regulatory requirements. This is the flagship of data sovereignty: your files, chats, calendars, and documents live on your server, under your jurisdiction, with GDPR compliance by architecture rather than by contract.

With over 7,700 GitHub stars and thousands of Cloudflare employees using it daily across every function, Cloudflare OS delivers an open-source AI workspace where every employee gets a personal agent grounded in company context, systems, and skills — not a generic chatbot but a programmable workspace that builds real applications, automates workflows, and connects to internal tools through governed access. The Code Mode agent writes and immediately executes code snippets to perform arbitrary tasks, build full-stack Gadgets with client code, server code, APIs, and durable SQLite state, debug errors, and test results within isolated sandboxes. Gadgets are private application instances running in separate sandboxes — each document, spreadsheet, or tool is its own secure runtime that cannot leak data even to attackers with access to other Gadgets. Blueprints enable sharing application code as templates that others instantiate with independent state, credentials, and resources. Gatekeepers provide security governance giving system owners precise control over what agents can see, change, and when human approval is required before actions execute. Built on Cloudflare Workers using Durable Objects for workspace persistence, Dynamic Workers for Gadget execution, and Facets for access management. Zero Trust security via Cloudflare Access verifies every user and request before granting access. Real-time collaboration lets colleagues use shared Gadgets. Deploy to your own Cloudflare account or self-host on workerd, the open-source Workers runtime, on your own servers. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. Apache-2.0 licensed.

Host your own email, files, calendars, and passwords on a single server with YunoHost, a server operating system that puts every app behind one web admin and one shared login. Browse a catalog of more than 500 apps, such as Nextcloud, WordPress, and Vaultwarden, filter by quality level, and install in a few clicks, or paste a Git URL for a custom app. Each person signs in once at a portal that shows a tile for every app they may open, and apps with single sign-on skip their own login screen. Groups and per-app permissions control access, including public access for visitors, and the Admins group adds web admin, SSH, and sudo. A full mail stack handles incoming and outgoing email per domain with DKIM signing, and Let's Encrypt certificates renew automatically. The domain screen suggests the DNS records you need and can push them to a supported registrar's API, while free .nohost.me, .noho.st, and .ynh.fr subdomains configure themselves. Backups bundle system settings, mail data, and chosen apps into downloadable archives that can be restored selectively from the admin or the command line. Twice a day a built-in diagnosis checks DNS records, mail setup, and system resources, then emails the admins if anything needs attention, with a firewall editor and fail2ban protection alongside. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. AGPL-3.0 licensed.

Modoboa turns a bare mail server into a managed hosting platform, with one web console for domains, mailboxes, aliases, and quotas, plus a full webmail for the people using them. Roles separate super administrators, resellers, domain administrators, and ordinary users, with caps on how many mailboxes and aliases each administrator may create and daily sending limits per domain or mailbox. The webmail offers conversation view, folder subscriptions, scheduled sending, attachments, and search across headers and message bodies. Calendars and address books sync with standard clients, and calendars can be shared. Each user writes Sieve filters and autoreplies in the browser. Deliverability checks cover MX records and DNSBL listings, DKIM keys are generated per domain, and DMARC aggregate reports become per-domain visual reports. Amavis quarantine pages and an Rspamd frontend help with spam. Traffic graphs show message volume. Accounts authenticate against the local database, LDAP, Active Directory, or an existing SMTP server, with TOTP codes or WebAuthn security keys as a second factor. Thunderbird and Outlook configure themselves through built-in autoconfig and autodiscover endpoints. An IMAP migration tool pulls mailboxes from another provider as each person signs in. Administrators can brand the console with custom logos, extend it through plugins, and automate it through a documented REST API. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. ISC licensed.

Running your own mail server usually means assembling five services and praying over DNS records; LanQin Email ships the whole stack in one container. Readers switch between mailboxes, search, label, star, and file messages into folders, then compose with a rich-text editor that handles fonts, colors, code blocks, attachments, emoji, and scheduled sending. Contacts, signatures, inbox rules with automatic forwarding, sender blacklists, and mail statistics make it a daily client rather than a demo. Administrators run the postal side from the same panel: add domains and generate DKIM keys, follow the DNS record checklist the system verifies for you, create mailboxes, set delivery aliases and catch-all addresses, and audit every message on the server. Accounts sign in with passwords or OAuth single sign-on, protected by TOTP two-factor codes and bot checks, while permission groups cap attachment size, sending rate, and mailbox count per user. Users can even request their own mailbox and wait for approval instead of filing a ticket. For programs, an Open API with bearer tokens sends mail idempotently and reports delivered, bounced, complained, rejected, and deferred events back through webhooks. External Gmail and Outlook accounts can be aggregated over IMAP, and a client-configuration page shows every IMAP, POP3, and SMTP setting in one place. A multi-container layout remains for debugging the stack piece by piece. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. GPL-3.0 licensed.

Kurrier unifies email, calendars, contacts, and file storage in a single web interface that connects to any email provider you already use. The Next.js frontend with Nitro API worker deploys via Docker Compose on PostgreSQL and Redis, delivering a cohesive workspace where IMAP/SMTP mailboxes from Gmail, Outlook, or corporate servers sit alongside transactional providers like AWS SES, SendGrid, Mailgun, and Postmark. Automatic inbox building handles threads, attachments, sent items, and deletion sync through persistent background polling. The CalDAV backend enables full two-way calendar synchronization with iOS, macOS, Android via DAVx5, and Thunderbird, supporting event invitations, RSVP processing through the inbox, timezone-aware scheduling, and contact-aware attendee linking. CardDAV contacts sync bidirectionally across all devices with unified name, avatar, and email resolution. Kurrier Drive provides integrated file storage through WebDAV locally or S3-compatible backends for cloud storage. Multiple identities and domains let you manage several email accounts from different providers in one interface, with fast local search indexing subjects, senders, and content without dependency on external APIs. The API-first architecture exposes clean endpoints for automation and custom integrations. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. AGPL-3.0 licensed.

Transforming your Stalwart Mail Server into an all-in-one private communication hub, Bulwark Webmail delivers fast web-based email, collaborative calendars, shared contacts, and cloud files in a single unified interface. Users can manage multiple email accounts from an integrated inbox with conversational message threading, nested organizational tags, scheduled delivery, and instant full-text search across thousands of archived messages. The rich text composer provides markdown shortcuts, inline image embedding, reusable canned response templates, and automated draft synchronization. Team members can coordinate schedules across day, week, month, and agenda calendar views with drag-to-reschedule adjustments, interactive iMIP meeting invitations, and external CalDAV calendar subscriptions. The integrated address book organizes individual contacts into custom groups with full vCard import and export support, while the files module lets users browse server storage, preview incoming attachments, and upload documents directly through the browser. Built-in security safeguards enforce multi-factor authentication, cryptographic S/MIME signatures, client-side encryption at rest, and automated HTML luminance remapping to keep dark emails legible. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. AGPL v3 licensed.

Running a proper mail server used to mean stitching together half a dozen daemons; maddy folds the whole stack into one binary with one configuration file. It receives mail as your MX, sends as your MTA, stores messages for IMAP clients, and signs and verifies with DKIM, SPF, DMARC, DANE, and MTA-STS so other servers actually trust what you send. The design is composable: checks, modifiers, tables, and delivery targets snap together in the config, so spam scoring, address rewriting, and routing rules read like a pipeline instead of a pile of interlocking config files. Outbound mail queues with retries and backoff, inbound delivery lands in IMAP storage backed by SQLite or PostgreSQL, and a built-in ACME client keeps TLS certificates renewed, including DNS-01 providers. Milter support lets existing filters join the pipeline, authentication spans SASL mechanisms and Dovecot delegation, and Prometheus metrics watch queue length and delivery health from your usual dashboards. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. GPL-3.0 licensed.

Your entire mail system can live in one self-hosted suite with OpenMail, from SMTP, IMAP, and POP3 delivery to three-pane webmail and the admin console that runs it. Standard clients such as Thunderbird, Apple Mail, and phone apps connect over SMTP ports 25, 587, and 465, IMAP ports 143 and 993, and POP3 ports 110 and 995, while people use the three-pane webmail with folder tree, conversation list, and reading pane at port 3000. You read, write, reply, forward, batch-organize, drag messages between folders, filter stars, search sender, subject, and body text, and follow conversations threaded automatically by their References headers. The rich-text composer autocompletes recipients, accepts dragged attachments and pasted screenshots, saves drafts every 12 seconds, sends on a schedule, and inserts reusable templates imported from HTML or generated with AI. Any OpenAI-compatible endpoint can draft replies, translate mail into twelve languages, and summarize messages, with provider keys encrypted on your server. Administrators get real-time mail statistics with 14-day send and receive trends, user quotas and bans, multi-domain aliases and catch-all addresses, outgoing queue visibility, and audit logs. Adding a domain generates DKIM keys and copy-ready SPF, DKIM, and DMARC DNS records with one-click checks, while rule-based spam scoring, TOTP two-factor authentication, and role-based permissions protect accounts in ten interface languages including right-to-left Arabic and Urdu. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.