Install

MailBox Ultra ships as a native macOS application bundle (.app) packaged inside a .dmg for drag-and-drop install. Universal builds run natively on both Intel and Apple Silicon.

Requires macOS 11 (Big Sur) or newer. Windows and Linux builds are not produced.

#🚀 One-line install

sh
curl -sSL https://raw.githubusercontent.com/MPJHorner/MailboxUltra/main/scripts/install.sh | bash

The script detects your arch (arm64 or x86_64), downloads the matching .dmg from the latest release, mounts it, copies MailBox Ultra.app into /Applications, ejects the DMG, and clears the Gatekeeper quarantine flag so first launch doesn't need a right-click. Override the destination with MBU_INSTALL_DIR=~/Applications curl … | bash if you don't want it system-wide.

After it finishes:

sh
open '/Applications/MailBox Ultra.app'    # or Spotlight → "MailBox Ultra"

#Manual — download the .dmg

If you'd rather not pipe a script, do it by hand:

  1. Go to the latest release.
  2. Download MailBoxUltra-2.0.0-universal.dmg (or the per-arch DMG if you prefer).
  3. Open the DMG and drag MailBox Ultra.app into the bundled Applications shortcut.
  4. Eject the DMG. Find MailBox Ultra in /Applications or via Spotlight.

#First launch — Gatekeeper

The build is unsigned (no Apple Developer ID), so macOS will refuse to open it on the first double-click. Two ways through:

Option A — right-click → Open (one-time prompt):

Right-click MailBox Ultra.app in /Applications, choose Open, click Open in the dialog. Subsequent launches just need a normal double-click.

Option B — clear the quarantine flag in Terminal (skips the prompt entirely):

sh
xattr -d com.apple.quarantine /Applications/MailBox\ Ultra.app

Either way, the app launches, the SMTP server binds 127.0.0.1:1025, and the toolbar shows the URL it picked.

#Verify the download

Each release ships a .sha256 companion file. Verify before opening:

sh
shasum -a 256 -c MailBoxUltra-2.0.0-universal.dmg.sha256

#Build from source

Requires Xcode Command Line Tools (xcode-select --install) and a recent Rust toolchain (rustup works).

sh
git clone https://github.com/MPJHorner/MailboxUltra.git
cd MailboxUltra
make icon         # rasterise icon/icon.svg → AppIcon.icns (one-time, committed)
make app          # build target/<arch>/release/MailBoxUltra.app for the host
open target/aarch64-apple-darwin/release/MailBoxUltra.app

Other targets:

Command What you get
make run Debug build via cargo run, no .app bundle. Fastest iteration.
make app Host-arch .app bundle (Apple Silicon Mac → arm64; Intel Mac → x86_64).
make app-arm Apple Silicon .app regardless of host.
make app-x86 Intel .app regardless of host.
make app-universal Universal .app (lipo-merged Intel + Apple Silicon).
make dmg Wraps the host .app in a .dmg with a drag-to-Applications symlink.
make check Pre-commit gate: cargo fmt --check, cargo clippy -- -D warnings, cargo test.

#Updating

There's no auto-update. To upgrade, download the new release .dmg, drag the new .app into /Applications (replacing the old one). Settings persist in ~/Library/Application Support/com.mpjhorner.MailBoxUltra/.

#Uninstall

sh
rm -rf "/Applications/MailBox Ultra.app"
rm -rf "$HOME/Library/Application Support/com.mpjhorner.MailBoxUltra"

The second line wipes saved Preferences. If you only want to reset the app to defaults but keep it installed, open Preferences and click Reset to defaults.

#Code-signing & notarisation

The public release is unsigned. If you have a Developer ID certificate and want signed local builds, set APPLE_CERT_ID in your environment before make app — the build script picks it up and runs codesign over the bundle.

#Next

Quick start →