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Install Mailbox Client

Two paths: install from the Mac App Store or build from source with Xcode. Then export your Gmail with Google Takeout and import the archive.

Step 1

Export your mail from Gmail

Google Takeout lets you export everything in Gmail as a standard MBOX archive. It's the supported, no-strings way to leave or back up your mailbox.

1

Open Google Takeout

Sign in to your Google account and visit takeout.google.com.

2

Pick Mail only

Click Deselect all, scroll to Mail, enable it. Inside the Mail options keep the format as MBOX.

3

Pick all labels (or a subset)

By default Takeout exports every label. You can narrow it down to specific labels if you want a smaller archive.

4

Choose delivery and download

Pick "Send download link by email" and a 2 GB split size (Takeout will produce one or several .zip files). Wait for Google's email and download the archives. Inside each .zip there's a .mbox file.

Tip. A 10-year archive can easily be 5–20 GB. Make sure you have free disk space before importing.
Step 2

Get Mailbox Client

Two installation paths are supported. Pick the one that matches your situation.

Option A — Mac App Store (recommended)

Mailbox Client will be distributed on the Mac App Store. Once available, you'll be able to install it like any other app and updates will arrive automatically.

Option B — Build from source

If you want to follow development or contribute, build from the public repository:

  • Install Xcode 16 or newer.
  • Clone the repository: git clone https://github.com/lcajigasm/gmail-importer.git
  • Open Gmail importer.xcodeproj in Xcode.
  • Select the Gmail importer scheme.
  • Build and run with ⌘ + R.
Note. The Xcode project is still named "Gmail importer" for historical reasons — the user-facing product is Mailbox Client.
Step 3

Import your archive

Open the app and bring your MBOX files in.

1

Click Import MBOX…

The button lives in the toolbar at the top of the main window.

2

Pick one or more files

The system file picker lets you select multiple .mbox files at once. Each one will become its own library.

3

Wait for the progress UI

You'll see five steps: prepare, copy, parse, save, reindex. The duration depends on the size of your archive (a 5 GB MBOX typically takes a few minutes on Apple silicon).

4

Start exploring

Use the Libraries and Labels sidebar to filter, type into the search field to find messages instantly, and click any message to read it.

Step 4 (optional)

Tune Settings

Mailbox Client ships with sensible defaults, but four toggles are worth a look.

General

Theme (Light / Dark / System), interface language override.

Intelligence

Enable on-device summaries, categorization and reply drafts.

Spotlight

Index messages into Core Spotlight, reindex, or wipe the index.

iCloud

Enable private CloudKit sync between Macs and review status.

Troubleshooting

If something goes wrong

A short list of common issues during install and import.

  • "This MBOX file looks empty." Make sure you unzipped the Google Takeout archive. The actual .mbox file is inside the .zip.
  • Import takes forever. Importing several gigabytes is CPU-intensive. Plug into power and leave the app open in the foreground.
  • "Apple Intelligence panel is not showing." You need an Apple silicon Mac on macOS 15.4 or later, with Apple Intelligence enabled in System Settings and available in your region.
  • "Garbled characters in some messages." Set the environment variable MBOX_CHARSET_DEBUG=1 in the Xcode scheme and re-import to see which charset was used. Report it via Support.