MailCraft

Local-first email for creators; an open-source, clean-room alternative to Microsoft Outlook, rebuilt in pure Rust.

The mail workflow you already know (folders, a message list grouped by date, a reading pane, Reply / Reply all / Forward, flags, Archive, Delete, Send / Receive) over IMAP and SMTP, JMAP or Exchange Online, with a calendar and people beside it. Mail is cached on your computer, so it opens instantly, searches fast and stays readable offline. Your password stays in the system keychain and only ever goes to your own mail server.
By the ArtCraft team. Tracked in storytold/artcraft#2177.

Search across every folder, offline, with from:, subject:, has:attachment, is:unread; conversations; dark mode.

Write in place: replies quote the original under your signature, with attachments, Cc/Bcc and drafts.

Why MailCraft

• Familiar. Three panes, the ribbon's everyday buttons and the shortcuts people already use: Ctrl+N new, Ctrl+R reply, Ctrl+Shift+R reply all, Ctrl+F forward, Ctrl+Q / Ctrl+U read / unread, Insert flag, Delete, Backspace archive, Ctrl+Shift+V move, F9 send / receive, Ctrl+Enter send, Ctrl+E search, ↑ ↓ to walk the list. Drag messages onto a folder to move them.
• Local-first. Every folder is cached on disk with the IMAP sync state (UIDVALIDITY, UIDNEXT, HIGHESTMODSEQ), so a refresh costs a handful of round trips and changes made offline are replayed when you reconnect. See docs/sync.md.
• Private. No cloud relay: the app talks to your mail servers directly over TLS. Passwords (or OAuth sign-ins) live in the OS keychain (Windows Credential Manager, macOS Keychain, Secret Service). HTML mail is shown as formatted text and pictures from the web load only when you ask, so trackers stay quiet.
• Media-aware. Picture attachments preview inline, text-like files and attached emails open in a preview, and files a Craft app edits get Open in PdfCraft / WordCraft / GridCraft…; any attachment opens in its default app or saves anywhere.
• Fast. The message list only lays out the rows on screen; search uses an inverted index over headers, cached bodies and attachment names.
• Built for agents. Every action is a command with an id. The same commands drive the ribbon, shortcuts, the CLI (mailcraft-cli run mail.reply) and startup scripting (--cmd).
• Never crash. No unwrap/expect/panic outside tests, hostile-input caps in the IMAP parser, a test that runs every command with junk parameters, and Session::run catches any panic.
• Open. MIT OR Apache-2.0, clean-room: built from the RFCs and public behaviour, every asset original (icons are drawn in code).

What works today

Area	Highlights
Accounts	Any IMAP + SMTP or POP + SMTP provider (POP mail is kept in folders on this computer, starting from an existing .pst if wanted), JMAP (RFC 8620/8621), Exchange Online through Microsoft Graph, or an organisation's own Exchange server through EWS (NTLM or Basic sign-in, found with Autodiscover, calendars and contacts included); several accounts with an All Inboxes favorite; server settings found from the address (the domain's autoconfig, the Mozilla ISPDB, MX and SRV records); Gmail and Microsoft 365 sign-in through the browser (OAuth 2.0); SSL/TLS or STARTTLS; passwords in the system keychain; Outlook data files (.pst) open as mailboxes of their own, with their contacts and calendar, and any account exports to one
Sync	Folder list with special-use roles (RFC 6154); per-folder incremental sync (new mail, flag changes via CONDSTORE, deletions via QRESYNC); UIDVALIDITY resets; IDLE on the Inbox for instant new mail; newest messages prefetched for offline reading; changes made offline replayed; back-off reconnects; desktop notifications for new mail
Reading	Date-grouped list (Today, Yesterday, weekdays, Last week…), unread bars and bold, flags, attachment and replied markers, previews; reading pane right, bottom or off; double-click opens a message in its own window; conversations (JWZ threading); HTML shown formatted (headings, lists, links, quotes, colours, tables) with web pictures on request, remembered per sender; picture, PDF and video thumbnails; attachments dragged out to other apps; Print, Save as PDF, Save as .eml; arranged by date, sender, recipient, subject, size, flag or attachments, either way round; filters for unread, flagged, files, categorized, important and to or Cc me; a minimizable folder pane
Organising	Delete (to Deleted Items; permanent there, with confirmation), Archive, Report junk / Not junk, Move to (dialog or drag), Read / Unread, Flag, Pin, Snooze, colour categories, Mark all as read; Focused / Other; inbox rules; filters: Unread, Flagged, Has files; multi-select with Ctrl and Shift; folders created, renamed, moved and deleted; favourites; Undo (Ctrl+Z); Ignore a conversation (its later replies go to Deleted Items)
Writing	New, Reply, Reply all, Forward (with attachments); formatting (bold, italic, lists, headings, quotes, links) sent with a plain-text alternative; pictures inserted or pasted inline; To / Cc / Bcc suggested from mail you've seen; attachments up to 25 MB; signatures; drafts saved to the server; an Outbox for mail written offline; High / Low importance and read receipts; drafts that can't reach the server are kept and saved when it's back
Calendar and people	Day, week and month views; events with recurrences and time zones; meeting invitations by mail (accept, tentative, decline, inviting guests); an address book; synced with CalDAV / CardDAV
Mailbox	The File page: account settings, automatic replies (Sieve, JMAP or Exchange), the space used, emptying Deleted Items and Junk Email, rules, Options; Work offline; each account in one .mailcraft data file in Documents\MailCraft Files, movable as Outlook's are
Search	Offline, all folders or this folder; bare words match word prefixes; "phrases", from:, to:, subject:, body:, has:attachment, is:unread, is:flagged, -negation
Languages	English, Español, Français, Deutsch, Português (Brasil), Italiano, Русский, 日本語, 한국어, 简体中文, 繁體中文, العربية, עברית: following the system or chosen in Options; right-to-left mail reads right to left
Platforms	Windows, macOS, Linux (egui on the GPU), and the browser (WebAssembly; JMAP accounts)

The full list of what's missing, ranked, is in docs/gaps.md.

Quick start

Installers come from the Releases page once a release is cut: .msi and a portable zip for Windows (x64, x86, ARM64), a .dmg for macOS (universal), AppImage, .deb, .rpm, Flatpak and .tar.gz for Linux (x86_64, aarch64, riscv64), and a FreeBSD tarball. To run from source:

cargo run --release -p mailcraft -- --sample

--sample opens a local-only sample mailbox, so you can try everything without a server. Run without it to add your own account (the gear button, or the welcome screen).

From the command line (passwords come from MAILCRAFT_PASSWORD or a prompt, never stored):

cargo run -p mailcraft-cli -- add --email you@example.com
cargo run -p mailcraft-cli -- add --email you@example.com --imap mail.example.com:993 --smtp mail.example.com:465
cargo run -p mailcraft-cli -- add --email you@fastmail.com --jmap https://api.fastmail.com/jmap/session
cargo run -p mailcraft-cli -- test
cargo run -p mailcraft-cli -- sync
cargo run -p mailcraft-cli -- list --limit 10
cargo run -p mailcraft-cli -- search "from:zoe has:attachment"
cargo run -p mailcraft-cli -- send --to friend@example.com --subject "Hello" --body "Sent from MailCraft"
cargo run -p mailcraft-cli -- commands

The browser version (JMAP accounts; see packaging/web/README.md):

cd apps/mailcraft-web && trunk serve

Then open http://127.0.0.1:8774/?sample for the sample mailbox.

The desktop app and the CLI share the cache (%APPDATA%\MailCraft, ~/Library/Application Support/MailCraft or ~/.local/share/mailcraft; override with --data DIR or MAILCRAFT_DATA).

Architecture

Layer	Crate	Job
L0	model	accounts, folders, message keys, flags, jobs and events, JWZ threading, search queries and index, dates, IMAP UTF-7
L1	mime	parse messages for the list and reading pane, HTML → text, attachments, build outgoing mail, reply / forward drafts
L1	store	the local-first cache: folder state, message sources, pending offline changes, the Outbox; atomic writes
L1	print	messages as PDF pages, with the interface font embedded
L2	jmap	the JMAP transport, async over any HTTP client: the desktop's and the browser's fetch
L3	net	native only: IMAP client on imap-proto, the sync algorithm, SMTP via lettre, JMAP push, Microsoft Graph, Exchange Web Services (NTLM), CalDAV/CardDAV, ManageSieve, POP3, HTTP, DNS, autoconfig, OAuth, Outlook data files, per-account worker threads
L4	engine	the sans-I/O session: views, selection, compose, search, the command registry; queues jobs, applies events
L6	ui-egui	the egui front end (thin: reads the session, runs commands)
apps	mailcraft, mailcraft-cli, mailcraft-web	the desktop app, the command line and the browser version

The engine never touches the network: it emits Jobs and applies Events, which the app connects to the net worker pool. Tests drive it with scripted events, and in-memory IMAP and JMAP servers (and Graph, CalDAV/CardDAV and ManageSieve) servers test the real clients and sync code. Details in docs/architecture.md.

Quality gate before every commit: cargo xtask ci (fmt, clippy -D warnings, tests, layering, assets, wasm).

Packaging and releases

The scripts in packaging/ build every installer (packaging/linux/package.sh, packaging/macos/package.sh, packaging/windows/package.ps1, packaging/freebsd/package.sh), and the GitHub workflows run them through the shared Craft pipelines in storytold/craft-common-actions:

Workflow	When	What
ci.yml	every push and pull request	cargo xtask ci on Windows, macOS and Linux
freebsd.yml	pushes to main, dependency changes	build and test in a FreeBSD VM
windows-arm64.yml	pushes to main, weekly	cross-build the ARM64 MSI, install and run it on Windows 11 ARM
packaging-lint.yml	packaging or workflow changes	actionlint, shellcheck, PowerShell, WiX, desktop entry, AppStream, Flatpak
release.yml	a push to the release branch, or by hand	sign, notarize and package every platform, then draft a GitHub Release

The version lives only in [workspace.package] of Cargo.toml (cargo xtask version, cargo xtask version set 0.2.0). App icons are drawn by cargo xtask icons.

License and credits

MIT OR Apache-2.0. Built on mail-parser and mail-builder (Stalwart Labs, Apache-2.0 / MIT), imap-proto (MIT / Apache-2.0), lettre (MIT), rustls and ring, html2text (MIT), ttf-parser and miniz_oxide (MIT / Apache-2.0), quick-xml (MIT), hayro (MIT / Apache-2.0), outlook-pst (Microsoft, MIT), outlook-pst-rw (MIT), drag (MIT / Apache-2.0), x11rb (MIT / Apache-2.0) and egui. Microsoft Outlook is a trademark of Microsoft; MailCraft is not affiliated with it and uses none of its code, icons or assets.