Self-hosted email for your own domains, running entirely on Cloudflare. There's no mail server to patch and no IP reputation to nurse: Email Routing receives, Email Sending delivers, a single Worker with Durable Objects, D1, R2, and Queues handles everything in between, and a fast web client sits on top.
Status: early. Receiving, threading, search, sending, and delivery tracking work end to end. It's built for a few people on a few domains. Read the constraints before moving real mail onto it.
- Every address, one inbox. Any number of domains and addresses feed one mailbox. Filter by address in a
click. Group addresses like
family@deliver a copy to each person. +tagbecomes a label. Mail tome+receipts@lands under receipts automatically.- Rules file new mail. Label it, skip the inbox, star it, mark it read, or send it to Spam or Trash, by sender, recipient, subject, body, list, or any header, in the order you put them. A rule can also ask in plain English ("a receipt for something I bought"), which Workers AI checks of new mail that isn't spam, and each message says which rule filed it. Written through the API for now.
- Ask an assistant. The sparkles button, or Ctrl+. (⌘. on a Mac), opens a panel where you ask in plain words: find mail, label, archive, or star it, and write rules from what you describe. It acts only on your own mail, and anything that could lose mail, like Trash or Spam, waits for you to approve it.
- Set up and run from the app. Add domains, people, and addresses in the admin pages. Magnus turns on Email Routing and Email Sending in Cloudflare for you, and MTA-STS, so other servers deliver your mail only over an encrypted connection.
- Rejects during the SMTP session. Unknown recipients and blocked senders bounce before the message is accepted, so Magnus never sends backscatter. In the 30 days after a domain's mail moves to Magnus, mail to an address you haven't added yet is held instead, under Admin › Addresses, and adding the address delivers it.
- Real threading by
Message-ID/References, with a careful subject fallback. Replies thread in Gmail, Apple Mail, and Outlook too. - Conversations branch where they fork. When two people answer the same message, each reply hangs off it with its own follow-ups, and the history a reply quotes folds away behind a •••.
- Forwards that look like the original. Its HTML, images, and the files you keep go along, under a Gmail-style header, and the forward stays in the conversation.
- Full-text search, undo send, and a delivery badge on every sent message (delivered, bounced, …). Mail that didn't make it says who missed it, and Retry sends it again to just them.
- Write in markdown, see it formatted. Bold, lists, quotes, and links show as you type them, or from the bar over a selection. Mail goes out as HTML with a plain-text part that reads the same.
- Recipients autocomplete from everyone you've written to or heard from, and each address you send as can have its own signature, formatted the same way.
- Previews for photos, video, audio, and PDFs, in the app and on the page a file link opens. Video streams, so it plays and seeks without downloading first.
- Big files go as links. Whatever doesn't fit in a message is sent as a download link, like Gmail's Drive links. It keeps working until you stop sharing it from Sent.
- At home on a phone. Install it to the home screen, or as a desktop app, for its own icon and window. The list and a thread take turns filling the screen, Compose floats over the list and opens full screen with Send above the keyboard, and newsletters laid out for a desktop shrink to fit.
- Notifications for new mail on each device you turn them on for, in Settings › Notifications: the sender, subject, and first line, encrypted so the push service can't read them. On iPhone and iPad, add Magnus to the Home Screen first.
- Live updates over hibernatable WebSockets, so idle tabs cost nothing.
- Trash you can empty. Permanently delete trashed messages in a conversation or empty Trash for the addresses in view, with confirmation. Files still used by other mail stay; failed storage cleanup retries automatically.
- Bring your old mail. Sign in to Proton on Settings › Import mail and your mail comes over on its own, with its
folders, labels, stars, read state, and Sent, threaded like new mail; close the page whenever. Magnus runs Proton's
own Export Tool for it in a Cloudflare Container. Or drop an export: the
.mboxfrom Gmail's Takeout, Thunderbird's Mail folder, the folder Proton's Export Tool saves on your computer, or any folder of.emlor mbox files. Importing the same mail again adds nothing twice. - Hostile HTML stays contained: streaming sanitizer, strict CSP, sandboxed iframe, and remote images blocked until you ask.
- Sign in with a passkey, an emailed code, or a password you set, or Google if you add it. There's no sign-up; only people you add can get in.
- Raw messages are kept in R2, so a parsing bug can be fixed by replaying the queue. Mail that still can't be read after its retries goes to Failed, to retry or download, rather than being dropped. Permanent deletion removes unshared originals after the inbound retry window, and a replay cannot restore deleted mail.
You need a Cloudflare account on Workers Paid ($5/month, which includes 3,000 outbound emails) and a domain on Cloudflare DNS. Everything else for a few people fits in the included usage.
- Click Deploy to Cloudflare above. Cloudflare copies Magnus to your GitHub, creates its database, storage, and queues, and deploys it. Keep the pre-filled build and deploy commands; no secrets are needed here.
- Open the Worker's URL (
magnus.<your-subdomain>.workers.dev). It starts at setup. - Paste a Cloudflare API token, pick your domain, and create your account. Magnus turns the domain on and signs you in.
docs/DEPLOY.md covers the token's permissions, deploying from the command line, moving a domain over from another provider, and updating.
Internet ── SMTP ──▶ Email Routing ──▶ email() ──▶ raw .eml to R2 ──▶ Queue ──▶ queue(): parse ──▶ Mailbox DO
Browser ── HTTPS ──▶ fetch(): app + API ──────── RPC / WebSocket ────────────────────────────▶ Mailbox DO
Mailbox DO ── alarm ──▶ Email Sending ──▶ recipients
One Worker does it all:
| Part | Code | Role |
|---|---|---|
email() |
worker/mail/ |
Accepts or rejects at SMTP time, stores the raw message, queues it |
queue() |
worker/mail/ |
Parses queued mail into its mailbox; applies delivery events |
fetch() |
worker/, src/ |
The React app and its API: mail, setup, and admin |
Mailbox |
worker/mailbox/ |
One Durable Object (SQLite) per mailbox: threads, labels, search, outbox, live updates |
shared/ holds what the app and the Worker both use, and migrations/ the D1 schema, which the Worker
applies itself. docs/ARCHITECTURE.md covers the full design and its tradeoffs.
Needs Node 22+ and pnpm 10. No Cloudflare account required.
git clone https://github.com/Derpedyea/magnus && cd magnus
pnpm install
pnpm db:seed:local # an admin with one mailbox and three addresses
echo "DEV_USER_EMAIL=dev@localhost" > .dev.vars
pnpm dev # http://localhost:5173You're signed in as the seeded admin (DEV_USER_EMAIL only works on localhost). Send it some mail through
the real email() handler:
pnpm mail:test # → [email protected]
pnpm mail:test "[email protected]" [email protected] "Your receipt"
pnpm mail:test [email protected] [email protected] "Re: hi" --reply-to "<some-message-id@host>"Nothing is really sent locally. Outbound mail, sign-in codes included, is written to .wrangler/tmp/email/.
| Command | What it does |
|---|---|
pnpm dev |
The app and Worker in watch mode, with local D1/R2/Queues in .wrangler/state/ |
pnpm typecheck |
tsc for the app, Worker, and test fixtures |
pnpm test |
Unit tests and isolated Worker tests for mail, send alarms, and multi-user API permissions |
pnpm test:e2e |
e2e browser tests in e2e/, headless, on their own fresh seeded app, with agent steps on your Claude Code login; --headed to watch |
pnpm run deploy |
Typecheck, test, build, then deploy to your Cloudflare account |
pnpm cf-typegen |
Regenerate worker-configuration.d.ts after changing wrangler.jsonc |
- Web client only. No IMAP, POP, or JMAP, by design. Phones use the web app.
- Personal mail, not bulk. Cloudflare Email Sending is for transactional mail. Don't send newsletters from it.
- Outbound messages max out at 5 MiB including attachments (inbound allows 25 MiB). Bigger files, up to 100 MB each, go as download links instead.
Drafts autosave to your account and are available from Drafts on any signed-in device. Close keeps a draft; the trash button discards it. Conflicting edits from two devices can be kept as a separate copy.
Next up: forwarding. The full list is in the roadmap.