Download MailDeck
MailDeck is free and distributed as a DMG notarized by Apple. This site (k386.sub.jp) is the only official source. The app is in Japanese.
1.3.1 mistakes outdated version information (for 1.3.0) that was accidentally bundled inside the app for the latest release, so it never asks this site for a new version. No notice appears when a new version is released, and the menu item "MailDeck > アップデートを確認…" (Check for Updates) says "MailDeck は最新です" (MailDeck is up to date).
This is fixed in 1.3.2. Because 1.3.1 will not show a notice for new versions, please download the latest version from this page and replace the app the same way as in How to install. From 1.3.2 on, the app tells you when a new version is out. The large 1.3.1 DMG had the same cause (the site's files were bundled inside the app); 1.3.2 is smaller.
MailDeck 1.3.3
macOS 13 or later, Apple silicon only. Intel Macs are not supported.
Free DownloadBy downloading, you agree to the Privacy Policy & Disclaimer.
How to verify the file
You can check that the file is the official one in the Mac's Terminal app. These commands assume the file is in your Downloads folder.
spctl -a -vv -t open --context context:primary-signature ~/Downloads/MailDeck-1.3.3.dmg shasum -a 256 ~/Downloads/MailDeck-1.3.3.dmg
- If the first line shows "accepted" and "source=Notarized Developer ID", the file has been notarized by Apple.
- If the value from the second line matches the SHA-256 in the table above, the file has not changed since it was published.
Notarization is Apple's automated check for known malware. It does not guarantee the app's quality or behavior.
How to install
-
Open the DMG
Double-click the downloaded
MailDeck-1.3.3.dmg. -
Drag it to Applications
In the window that opens, drag the MailDeck icon onto the Applications folder.
-
Open MailDeck
Open MailDeck from the Applications folder. The first time, macOS asks whether you want to open an app downloaded from the internet. Click "Open".
-
Add a Google account
No accounts are set up at first. Add one from Settings (⌘,). See the User Guide.
YuOn the first-launch prompt, "Open" is fine.
If you use Homebrew, you can install it from Terminal instead. It downloads the same file from this site and checks its SHA-256 before installing.
brew install --cask kenji-miygauchi/apps/maildeck
How to update
Download the new DMG from this page and replace MailDeck in the Applications folder, following the same steps as installation. Your accounts and sign-ins are stored separately from the app, so they are kept.
MailDeck checks for a new version 5 seconds after launch and every 30 minutes, and shows the release notes when it finds one. You can also check from the menu "MailDeck > アップデートを確認…" (Check for Updates). From 1.3.3 on (Mac), pressing "アップデートして再起動" (Update and Restart) in that window downloads the new version from this site, checks its SHA-256, signature and Apple notarization, replaces the app and reopens MailDeck. Nothing happens unless you press it. Versions 1.3.2 and earlier only open this page from the notice, so please install 1.3.3 by hand once.
As described in the known issue above, 1.3.1 cannot find new versions, and the manual check says it is up to date. If you use 1.3.1, please replace it with the latest version from this page.
YuOn 1.3.1, please peek at this page now and then.
How to uninstall
-
(To remove sign-ins too) Reset MailDeck
Open "MailDeck > 設定…" (Settings) and press "MailDeckを初期化…" (Reset MailDeck) under "危険な操作" (Danger zone). All accounts and sign-ins are removed and the app returns to its first-launch state.
-
Move the app to the Trash
Quit MailDeck and move it from the Applications folder to the Trash.
-
(Optional) Delete the settings folder
Settings and sign-ins are stored in the folder below. Paste it into Finder's "Go > Go to Folder", then move the folder to the Trash.
~/Library/Application Support/maildeck
Release notes
1.3.3 September 30, 2026
- When a new version is found, pressing “Update and Restart” now downloads it from the official site, verifies it (SHA-256, signature and Apple notarization), replaces the app and reopens MailDeck (Mac). Your accounts and sign-ins stay as they are. Versions 1.3.2 and earlier only open the download page from the notice, so please install 1.3.3 from the download page once.
1.3.2 September 29, 2026
- Added "About this app". Open it from the menu (MailDeck > このアプリについて) to see the version, the copyright (© 2026 K386) and a link to the official site. It appears once on first launch and once after each update.
- The new-version notice and "アップデートを確認…" (Check for Updates) now find the latest release on the distribution site
- A smaller DMG: it no longer carries the previous version's files
1.3.1 September 14, 2026
- Added an in-app notice when a new version is published (does not work in 1.3.1 because of a defect)
- Shows the release notes and opens the download page in one click
- Added "アップデートを確認…" (Check for Updates) to the app menu (in 1.3.1 it always says the app is up to date)
- More stable profile picture display and account list
- Distributed as a DMG notarized by Apple
1.3.0 September 14, 2026
- Search Gmail in all accounts at once
- Collapse the account list to icons (⌘⌥S)
- "Close window" hides only the window while unread checks continue
- Links in emails open in your usual browser
- Clean View (hides Gmail's Chat, Meet and side panel)
- Several accounts signed in at once, with Mail, Calendar, Keep and Contacts
Only the latest version is available on this page.