Email and newsletters decision
Fastmail
You can build a usable self-hosted email+calendar for a single user or small group, but reproducing Fastmail’s full product (24/7 support, masked-email, polished native apps, and production reliability at scale) is expensive and time-consuming—so keep paying if you need the complete service.
Visit website↗Open-source builds that already do this
Every project below is open source and already does this job today. Fork one, self-host it, or take the parts you need — the build prompt further down assumes an empty file, and this is the shortcut past that. Licences differ; check the one on each card before you ship.
What a replacement has to do
- Host email for one or a few users: accept mail, store and index messages, provide webmail with search, sync calendars and contacts, and allow use of custom domains.
What it still won’t have
- 24/7 expert support from real people
- Masked Email (built-in disposable address management)
- Years of production-hardened reliability and backups at scale
- Polished native mobile apps and cross-device client polishing
- Integrated paid multi-user admin features and family plans
What remains hard
- Brand trust
We’ve been delivering a better service for over 20 years, growing all that time — because once you’ve tried it, you won’t settle for anything else.
First-year cost
Keep paying
Paying is—cheaper in year one.
On cash alone, building overtakes the subscription at 2 seats.
Money you would actually spend
Time you would spend
—
What you would spend
What we assumed
The verdict above measures whether you could build it. This one is only about money.
Runnable build prompt
Build a self-hosted private email+calendar service for a single user using Postfix (SMTP), Dovecot or a JMAP server for storage, PostgreSQL for metadata, an open-source full-text index for search (e.g. Elasticsearch or Postgres full-text), a React webmail frontend with Service Worker for offline, CalDAV/CardDAV or JMAP support for calendar/contacts, and an admin UI for domain and alias configuration. In scope: SMTP submission/relay, message storage and indexing, web UI with search/compose/offline, calendar and contacts sync, DKIM/SPF setup guidance, basic spam filtering (rspamd) and backups. Out of scope: mobile native apps, multi-tenant scaling beyond a few users, commercial-grade 24/7 support. Include TLS, DKIM/DMARC setup docs, automated backups, monitoring, error handling, and unit/integration tests for mail delivery, indexing, and web UI flows.
How we checked
How the score was reached
- Partly verdict base52
- An open-source build was found+5
- 5 cited sources+3
- Price verified on pricing page+3
- Evidence score63
The base comes from the verdict. Everything under it is a check that either happened or did not, and each one is a fact frozen in this record rather than a judgement made at render time — so the same evidence always produces the same number.
How scoring works →Cited sources · 5
Every page the run actually retrieved.
- official productFastmail — Home
- official pricingFastmail Pricing
- official docsFastmail Features
- open sourcemail-in-a-box/mailinabox
- open sourceMailu/Mailu
Integrity checks
What held up, and what did not.
