MailBackup

Archive and back up your email locally over IMAP — a native macOS app.

MailBackup connects to your IMAP accounts and keeps a local, offline copy of your mail as standard .eml files, indexed for fast full-text search. Everything stays on your Mac — nothing is sent anywhere else.

Features

• Multiple IMAP accounts with provider presets (Gmail, iCloud, Outlook, Fastmail, Yahoo, Purelymail, or any custom server). SSL/TLS and STARTTLS supported.
• Incremental, headers-first sync — UID-based; fetches envelopes first so the list fills instantly, then streams bodies. Uses BODY.PEEK[], so mail is never marked read on the server, and handles UIDVALIDITY resets.
• Background sync & scheduling — runs as an app-level task on a WAL-backed database (browse while syncing); optional per-account interval (hourly/daily). Pause globally or per account.
• Local storage — each message saved as a portable .eml on disk; metadata + a full-text index in SQLite. Paged loading keeps very large mailboxes fast.
• Search, sort & filter — full-text search per-folder or across all accounts; sort by date/relevance, filter by unread / with-attachments / date range, and saved searches in the sidebar.
• Conversation view — optional grouping into threads by subject.
• Reading — three-pane UI with an HTML viewer that blocks all remote content (no tracking pixels), Rich/Plain toggle, and savable attachments.
• Spotlight — archived messages are indexed so macOS system search finds them.
• Dashboard, Jobs & Log — sync status and stats, a live view of sync runs, and a persistent activity log.
• Menu bar — mirrors the dashboard and shows a sync icon while syncing; toggle off in Settings.
• Import — bring in existing .mbox, .eml, or ZIP-of-.eml archives (into a local, never-synced account).
• Export & print — a message as .eml or PDF, print it, or export a folder/account as a zip or Maildir.
• Notifications when a sync finishes or fails.
• Maintenance — verify archive integrity (and remove orphaned entries).
• Account management — edit connection details, change the password, pick which folders to archive, and remove an account (with its local archive).
• Privacy first — credentials in the macOS Keychain; optional at-rest encryption of .eml files (pair with FileVault for full coverage).

Install

Download the latest MailBackup-x.y.z.dmg from the Releases page, open it, and drag MailBackup into your Applications folder. Requires macOS 14 or later (Apple Silicon).

Opening a non-notarized build

These builds are not notarized (not signed with an Apple Developer certificate), so macOS Gatekeeper blocks them on first launch with a message like "MailBackup can't be opened because Apple cannot check it for malicious software." This is expected — open it once using any of these, and macOS remembers the choice:

• Right-click (or Control-click) MailBackup.app → Open, then click Open in the dialog.

• On macOS 15 (Sequoia) the right-click option may not appear. Try to open the app, then go to System Settings → Privacy & Security, scroll to the Security section, and click Open Anyway.

• Or, from Terminal, clear the quarantine flag:

  xattr -dr com.apple.quarantine /Applications/MailBackup.app

Prefer to verify the code yourself? Build from source (below) instead.

Build from source

Requires Xcode 16+ (developed against Xcode 26 / Swift 6.3) and XcodeGen. The Xcode project is generated from project.yml and is not checked in.

brew install xcodegen          # once
xcodegen generate              # creates MailBackup.xcodeproj
open MailBackup.xcodeproj       # then press Run in Xcode

Or build from the command line:

xcodebuild -project MailBackup.xcodeproj -scheme MailBackup -configuration Debug build

On first launch, an onboarding flow walks you through adding an account, picking folders, choosing an archive location, and running the initial sync.

Tip: for Gmail / iCloud / Outlook / Yahoo / Purelymail, use an app-specific password rather than your main account password.

Tech stack

• SwiftUI + the Observation framework, macOS-native.
• swift-nio-imap + swift-nio-ssl for a pure-Swift async IMAP client over TLS.
• GRDB for SQLite with an FTS5 full-text index, in WAL mode.
• A small built-in MIME / RFC 2047 parser for extracting searchable text, HTML bodies, and attachments.

Architecture

Sources/MailBackup/
├── App/          AppModel (root state), ActivityLog, RootView
├── Onboarding/   Multi-step setup wizard
├── Main/         3-pane window: Dashboard, Search, Jobs, Log, message viewer
├── IMAP/         Async IMAP client built on swift-nio-imap
├── Sync/         SyncEngine — incremental UID sync orchestration
├── Mail/         MIME + RFC 2047 parsing
├── Storage/      GRDB database, repository, .eml ArchiveStore, Keychain
└── Models/       Account, Folder, Message, and view models

The app stores its database and .eml archive under ~/Library/Application Support/MailBackup (the archive location is configurable during onboarding).

Development smoke tests

A few self-checks are wired into the binary behind environment variables and exit after running:

APP="$(find ~/Library/Developer/Xcode/DerivedData/MailBackup-*/Build/Products/Debug -name MailBackup -path '*MacOS*' | head -1)"

MAILBACKUP_STORAGE_TEST=1 "$APP"   # migrations, .eml roundtrip, FTS, Keychain
MAILBACKUP_MIME_TEST=1    "$APP"   # MIME / RFC 2047 parsing
MAILBACKUP_EXPORT_TEST=1  "$APP"   # .eml + zip export

# Read-only end-to-end IMAP check (uses your own credentials, nothing is stored):
MAILBACKUP_IMAP_HOST=imap.fastmail.com \
MAILBACKUP_IMAP_USER=you@example.com \
MAILBACKUP_IMAP_PASS='app-password' \
"$APP"

Privacy & security

• All mail is stored locally; nothing is uploaded or shared.
• Passwords live in the macOS Keychain.
• The HTML viewer blocks every network request, so remote/tracking content never loads.

Status

This is an early, actively developed project. Contributions and issues are welcome.