Self-Hosted Email Servers

The hardest "useful self-hosted thing" to do well — deliverability, spam filtering, DNS hygiene, all on you. The Email page covers transactional senders (Resend / Postmark / SES); this page is for "I want to own the entire mail stack." If you don't have a strong reason, use a managed sender — but if you do, these are the tools.

Bundled stacks (the realistic option)

• ★ Mailcow: dockerized — Postfix + Dovecot + Rspamd + SOGo, all Compose-orchestrated, sane defaults, web admin UI. The default in 2026 for "I want a working mail server in an afternoon."
  • https://github.com/mailcow/mailcow-dockerized
• ★ Mail-in-a-Box — single-script Ubuntu installer; Postfix + Dovecot + Roundcube + Z-Push + Nextcloud Calendar/Contacts. Opinionated, "no choices to make." Great for a personal domain.
  • https://github.com/mail-in-a-box/mailinabox
• ★ Mailu — Compose-based; modular; lighter than Mailcow; admin UI; supports cluster mode.
  • https://github.com/Mailu/Mailu
• Modoboa — Django admin UI on top of Postfix / Dovecot / Rspamd / Radicale.
  • https://github.com/modoboa/modoboa
• iRedMail — long-running scripted installer; community + paid Pro.
  • https://github.com/iredmail/iRedMail
• Poste.io — single-container all-in-one; closed-source admin, free + paid tiers.

Modern single-binary servers

• ★ Stalwart Mail Server — Rust; SMTP + IMAP + JMAP + spam filter + admin UI in one binary. Modern protocol support (JMAP, MTA-STS, MTA-Hooks). Rising fast. Excellent docs.
  • https://github.com/stalwartlabs/mail-server
• ★ Maddy — Go; single binary; SMTP + IMAP; minimal config. The "small team mail server" pick.
  • https://github.com/foxcpp/maddy
• WildDuck — Node; HTTP / IMAP / POP3 / LMTP; Mongo-backed; HA-friendly; Zone-MTA pairs with it for outbound.
  • https://github.com/nodemailer/wildduck

Outbound-only (transactional sender, self-hosted)

• ★ Postal — full mail server with focus on transactional sending; Mailgun-shape API; tracking; webhooks.
  • https://github.com/postalserver/postal
• Cuttlefish — Ruby outbound mail server; small.
  • https://github.com/mlandauer/cuttlefish
• Halon MTA — closed-source commercial; outbound only at scale.

Components (DIY stack)

• Postfix — the SMTP MTA. Mature, documented to death.
• Dovecot — IMAP / POP3 server.
• Rspamd — modern spam filter; Lua-based; faster + better than SpamAssassin.
  • https://github.com/rspamd/rspamd
• OpenDKIM / OpenDMARC — DKIM signing + DMARC enforcement.
• Roundcube — webmail; PHP; the long-running default.
  • https://github.com/roundcube/roundcubemail
• SOGo — webmail + CalDAV / CardDAV; Mailcow uses this by default.
  • https://github.com/Alinto/sogo
• Snappymail — Roundcube-shape modern alternative.
  • https://github.com/the-djmaze/snappymail

Deliverability essentials

• ★ SPF / DKIM / DMARC — set these correctly or your mail goes to spam. Mailcow / Mail-in-a-Box / Stalwart configure them automatically.
• ★ Reverse DNS (PTR) — your IP must resolve to a name that resolves back. Required by Gmail / Outlook.
• Warm-up the IP — ramp slowly; sending 10k cold = blocked.
• Don't run mail on a residential IP. Most ISPs block port 25; even if not, you're on every blocklist already.
• Postmaster Tools (Google) + Microsoft SNDS — feedback loops; sign up.
• MTA-STS + TLS-RPT + DANE — modern transport security; Stalwart and Mailcow support.
• MailTester.com, mail-tester.com, dmarcian — sanity-check before pointing real mail at the server.

Honest reality check

• Outbound to Gmail / Outlook is the hard problem. Even with everything correct, expect intermittent deliverability issues for the first months.
• Smarthost via SES / Postmark / Mailgun is the pragmatic compromise — your server handles inbound + storage; SaaS handles the last hop. Mailcow / Stalwart support this in one config knob.
• Backup MX or grey-listing — your inbox is single-server. Plan for it.

Patterns to adopt

• ★ Use a bundled stack, not raw Postfix. Mailcow or Mail-in-a-Box save weeks.
• Smarthost outbound through Postmark / SES if deliverability matters more than purity.
• Hetzner / OVH / Scaleway — cloud providers that don't block port 25 and aren't on blocklists.
• DKIM key rotation — annual.
• DMARC p=quarantine after a month of p=none reports clean; then p=reject.
• Fail2ban / Crowdsec in front — brute-force IMAP login attempts will start day one.
• Backup /var/vmail + the DB + the DKIM keys. All three are needed for restore.

Pick this if…

• Default for "personal domain mail": Mail-in-a-Box.
• Default for "small business mail": Mailcow.
• Modular Compose stack: Mailu.
• Modern protocol fan / single binary: Stalwart Mail Server.
• Tiny / Go-based: Maddy.
• Outbound-only transactional sender: Postal.
• Just want webmail in front of an existing IMAP: Roundcube or Snappymail.
• Don't want to do this yourself: Fastmail, Migadu, Purelymail, ProtonMail (managed alternatives).