Stalwart replaces the traditional Postfix + Dovecot + SpamAssassin + calendar-server stack with one Rust binary that speaks every standard mail and collaboration protocol natively. JMAP, IMAP4rev2, POP3, SMTP, CalDAV, CardDAV, and WebDAV all run inside the same process — no glue scripts, no sidecar daemons, no version conflicts between components. The pluggable storage architecture lets operators choose RocksDB for single-node deployments, FoundationDB for distributed clusters, PostgreSQL, MySQL/MariaDB, or SQLite for the data store, S3/MinIO/Azure Blob for message blobs, and Elasticsearch or Meilisearch for full-text search, with Redis or the internal engine backing rate limiters and session state. Security features include S/MIME and OpenPGP encryption at rest, automated DKIM key generation with DNS publication, DANE and MTA-STS transport security, automatic ACME TLS provisioning, granular ACLs, rate limiting, and IP banning. The browser-based admin console manages accounts, domains, groups, mailing lists, SMTP queues, DMARC/TLS-RPT/ARF reports, and every configuration object without touching a config file, while the self-service portal at /account gives end users password reset and encryption key management. Multi-tenant support with per-tenant quotas enables hosting-platform deployments, and coordinator-less clustering via Zenoh or NATS scales horizontally by adding nodes. Deploy via Docker or the standalone binary. 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.

Mail-in-a-Box turns a single Ubuntu server into a fully functional email system with one setup command, installing and configuring Postfix for SMTP, Dovecot for IMAP, Roundcube for webmail, and Z-Push for Exchange ActiveSync push notifications in an automated sequence that would take days to replicate manually. The DNS server auto-configures the full suite of email authentication records: SPF, DKIM, DMARC, DNSSEC with DANE TLSA, MTA-STS, and SSHFP. Getting all of these right is what separates email that lands in inboxes from email that lands in spam, and most manual installations never achieve the complete set. Nextcloud integration adds CardDAV contact sync and CalDAV calendar sharing across devices. Let's Encrypt certificates provision and renew automatically for every hosted domain. The web control panel manages users, aliases, custom DNS records, and automated backups, protected by TOTP two-factor authentication. Daily health checks verify that services run correctly, ports remain open, TLS certificates stay valid, and DNS records resolve properly, alerting you before delivery problems develop. Multiple domains and users operate from one installation with internationalized domain name support. Built-in HTTPS static site hosting uses the TLS infrastructure already in place. Runs on a dedicated RepoCloud VPS with guaranteed resources, root SSH, and browser serial console for complete email sovereignty. CC0 public domain licensed.

Mox offers a complete mail server stack in a single Go binary requiring no external dependencies. The quickstart command configures a working mail server with SMTP, IMAP4, webmail, and full DNS authentication in under ten minutes. SMTP handling includes a delivery server on port 25, a submission server for authenticated clients, and a queue with automatic retries and DKIM signing. IMAP4rev2 implementation provides full mailbox synchronization with CONDSTORE and QRESYNC for efficient offline clients, NOTIFY for multi-mailbox monitoring, MULTISEARCH across mailboxes, and TLS client certificate authentication via the EXTERNAL SASL mechanism. The built-in webmail provides browser-based reading and composing with message threading, attachments, and HTML rendering without requiring a separate web client. Email authentication implements SPF validation, DKIM signing and verification with automatic key rotation, DMARC policy enforcement with aggregate and failure reporting, DANE with DNSSEC-protected TLSA records, and MTA-STS for certificate verification. Junk filtering combines reputation-based sender scoring with Bayesian content analysis trained per account. The web administration interface manages domains, accounts, DNS records, TLS certificates, delivery queue, and real-time log viewing. Internationalized email addresses with EAI and IDNA support handle non-ASCII domains and mailboxes. Account autoconfiguration publishes settings for Thunderbird autoconfig and Outlook autodiscover. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT 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.