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.

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.

SnappyMail is a fast, privacy-respecting webmail client that connects to any existing IMAP and SMTP server, booting in under a second with a JavaScript payload of just 138 KB under Brotli compression (down from RainLoop's 8 MB fork origin). No database is required: all configuration and user data persists as flat files in a single volume, making Docker deployment trivially simple with the roughly 30 MB image consuming approximately 50 MB of RAM. Built-in PGP encryption supports three backends: OpenPGP.js v5 with ECDSA and EDDSA key generation, GnuPG integration, and Mailvelope browser extension compatibility, eliminating the need for separate encryption plugins. The integrated Sieve script editor enables users to create mail filtering rules, vacation auto-responders, and forwarding conditions directly within the web interface when connected to ManageSieve-capable servers on port 4190. Multi-domain administration allows a single instance to serve users across multiple IMAP servers with per-domain authentication routing. The admin panel manages extensions, security settings, branding customization, and domain configuration. GDPR-friendly by design, it removes all social media integrations, Gravatar lookups, and external tracking present in RainLoop. Dark mode strips background and font colors from email messages. The modified Squire HTML editor replaces CKEditor for composing rich-text messages. Scores 99% on Lighthouse performance. 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.

Five mailboxes, five tabs, five passwords: Gofer folds Gmail, Outlook, iCloud, and plain IMAP accounts into one browser tab where every inbox reads as a single, searchable whole. Threads, labels, and drag and drop keep triage fast, and search still finds the receipt from three years ago. Signatures and custom senders shape outgoing mail, scheduled sends wait for Monday morning, and a thread in another language translates in place. The calendar keeps pace with your mail: Google, Outlook, and CalDAV events sync both ways, invitations land in the inbox, and an RSVP or a Meet or Teams link attaches without leaving the message. Contacts follow the same rule through Google, Outlook, and CardDAV sync, so the address book you fix once is right everywhere. One install can serve a household or a small office, with separate users, encrypted credentials, blocked remote images, and passkey or authenticator sign-in for anyone who wants it. Classic, Minimal, and retro Express themes, flexible layouts, and push notifications make the daily inbox feel personal rather than administered. Leaving stays easy too: mailboxes export as mbox, mail moves between accounts, and a whole setup imports into another Gofer. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT 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.

Two decades of continuous development made Roundcube the standard-bearer of open-source webmail - a PHP IMAP client that gives any mail server a polished, application-like interface in the browser. It connects to whatever IMAP/SMTP stack you run - Dovecot, Postfix, a hosted mailbox - and delivers the full desktop-client experience: drag-and-drop message management, threaded conversation views, full MIME and HTML mail handling, find-as-you-type address book with groups and LDAP connectors, multiple sender identities, full-text search, and spell checking in dozens of languages. The default Elastic skin is genuinely responsive, working as well on a phone as a desktop, and the entire UI is skinnable. The plugin API is where deployments get shaped: managesieve exposes server-side filter management in the UI, enigma brings PGP encryption and signing via GnuPG, markasjunk trains spam filters, zipdownload batches attachments, password lets users change credentials, and attachment_reminder catches the classic forgotten-attachment email - among hundreds of community plugins. Built-in caching keeps large mailboxes fast, IMAP ACLs and shared folders support team setups, and XSS protection is engineered into the rendering pipeline. It scales from a single personal mailbox to unlimited users, backed by MySQL, MariaDB, PostgreSQL, or SQLite. GPL-licensed with regular security releases.

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.