Mac App Store Sandbox - Plugin and Automation Limitations in Airmail for macOS

Airmail for macOS is distributed exclusively through the Mac App Store. Like all apps on the Mac App Store, Airmail runs inside Apple's sandbox environment, which provides strong security and privacy guarantees. However, this environment can introduce limitations for users who rely on advanced workflows.

This article explains what the sandbox is, the most common limitations users may experience, and the alternatives we recommend.

What is the Mac App Store sandbox?

Apple requires every app distributed through the Mac App Store to run inside a sandbox. The sandbox isolates the app from the rest of the system, restricting which files it can access and how it can communicate with other applications. This protects users from malware and accidental data leaks.

The trade-off is that some advanced features that were possible in earlier non-sandboxed builds may not behave the same way under sandbox rules.

Common limitations users may notice

1. Third-party plugins. Older Airmail plugins (for example, certain read-receipt or PGP/GPG plugins distributed outside the Mac App Store) may stop loading after reinstalling Airmail or after a macOS update. The sandbox can block plugins that have not been updated for current security requirements.
2. Custom actions that trigger external scripts. Workflows that previously launched a shell script or sent data directly to another app via right-click custom actions may be restricted.
3. Direct app-to-app communication. Sending an email body, link, or selection to a non-Apple application that does not expose a standard system Share extension may not work as expected.
4. Access to files outside the user-visible folders. The sandbox limits Airmail's access to certain system locations; this is intentional and protects your data.

Recommended alternatives

If a workflow that depends on an older plugin or external script is no longer working, you can usually reproduce it inside the sandbox in one of the following ways:

Use Airmail's built-in features. Many requests we receive (read receipts, signatures, templates, snooze, send later, mute, custom swipes) are already covered by features available directly in Airmail Settings.

Use standard macOS Share extensions. The Share menu (square with an upward arrow) lets you send the current email or selection to any app that registers a Share extension. This is the supported way to move content from Airmail to another application under sandbox rules.

Use system-wide automation. Apple's Shortcuts app and Automator can chain actions across apps without breaking sandbox rules. A single keyboard shortcut can replace a multi-step custom action.

Use keyboard shortcuts inside Airmail. Airmail provides keyboard shortcuts for the most common operations; combining them with macOS text replacements often removes the need for an external script.

How to check your Airmail version

Open Airmail, then click the Airmail menu in the top menu bar and choose About Airmail. The version number and build are shown in the window that appears. We always recommend keeping Airmail and macOS up to date so that the latest sandbox-compatible features and fixes are available.

Need help with a specific workflow?

If a particular plugin or automation is essential to your work and the suggestions above do not cover it, please contact Airmail Support and describe the workflow in detail. Include your Airmail version, your macOS version, and a short description of what you are trying to accomplish. Our team will be happy to suggest a sandbox-compatible alternative or relay the request to the engineering team.

Updated on: 05/09/2026