# What Is ~/Library/Mail/Bundles on Mac?

> Mail/Bundles held old-style Apple Mail plug-ins. Since macOS Sonoma, Mail no longer loads them, so anything left in this folder is inert.

- Updated: 2026-10-10
- URL: https://fresh.ist/library/mail-bundles/

**TL;DR:** ~/Library/Mail/Bundles is where legacy Apple Mail plug-ins (.mailbundle files) were installed. macOS Sonoma ended support for them, and Mail now uses MailKit extensions that ship inside apps instead. On a current Mac, any bundle still sitting here does nothing and can be removed once you've checked which app it came from.

## Definition

- Full path: `~/Library/Mail/Bundles`
- Scope: user (inside your home folder)
- Freshist checks this folder when uninstalling an app. When you uninstall an app, Freshist looks here for items that belong to it. Matches on the app's bundle ID can be pre-selected; name-only guesses are labeled “not sure” and never pre-selected. Removed items go to the Trash, so you can undo.

## What used to live here

For many years, Apple Mail could be extended with plug-ins: bundles ending in `.mailbundle` that loaded straight into the Mail process. Tools for snoozing messages, filtering spam, filing mail into other apps or adding tracking features installed themselves into `~/Library/Mail/Bundles` (or, for every account on the Mac, into `/Library/Mail/Bundles`).

Apple introduced **MailKit** with macOS Monterey as the replacement. With MailKit, an app ships Mail extensions inside its own bundle, and you switch them on in Mail under **Mail → Settings → Extensions**. Starting with macOS Sonoma, Mail stopped loading the old plug-ins altogether. So on any Mac running Sonoma or later, this folder is a record of what was installed in the past, not something Mail reads.

## Why bundles are still here

Plug-in installers copied their bundle into this folder and then left it to you. Uninstalling the companion app rarely removed the plug-in, and upgrading macOS doesn't clean the folder either. A Mac that has been migrated from machine to machine with Migration Assistant can carry bundles that haven't worked in years.

You may also find a folder called `Bundles (Disabled)` beside it. Older versions of Mail moved incompatible plug-ins there after an update, and some setups ended up with several numbered copies.

| Item | What it is | Still used on Sonoma or later? |
|---|---|---|
| `~/Library/Mail/Bundles/*.mailbundle` | Legacy plug-in for your account | No |
| `/Library/Mail/Bundles/*.mailbundle` | Legacy plug-in for all accounts | No |
| `Bundles (Disabled)` | Plug-ins Mail already switched off | No |
| Mail extensions (MailKit) | Part of an installed app | Yes |

## Looking before you remove anything

Terminal can't read `~/Library/Mail` until you grant it Full Disk Access, so the simplest route is Finder: choose **Go → Go to Folder…** and enter `~/Library/Mail/Bundles`. If Terminal already has access, these commands only read:

```
ls -la ~/Library/Mail/Bundles
du -sh ~/Library/Mail/Bundles
```

To see which developer a bundle came from, Control-click it in Finder, choose **Show Package Contents**, and open `Contents/Info.plist`. The `CFBundleIdentifier` value names the vendor.

## Removing a leftover plug-in

1. Quit Mail.
2. Check whether the developer now offers a MailKit extension. If they do, install the current app and enable its extension in **Mail → Settings → Extensions**.
3. Move the old `.mailbundle` (or the whole `Bundles (Disabled)` folder) to the Trash.
4. Open Mail and confirm it starts normally, then empty the Trash.

Remove individual bundles rather than the `Mail` folder above them. `~/Library/Mail` also holds your downloaded messages, mailbox structure and local data, and none of that is a plug-in.

## When you uninstall a Mail add-on

Modern add-ons keep their extension inside the app, so deleting the app removes the extension with it. Mail drops the extension from its Extensions list on its own. For an older add-on, check this folder and `/Library/Mail/Bundles` by hand after uninstalling. The second one is shared by every account and needs an administrator password to change. Our guide to [uninstalling apps completely](/blog/uninstall-apps-mac-completely/) covers the other places an app tends to leave behind, such as [Application Support](/library/application-support/) and [Preferences](/library/preferences/).

## Sources

- [Use Mail extensions in Mail on Mac](https://support.apple.com/guide/mail/mlhla9a93cd5/mac) (Apple Support)
- [MailKit](https://developer.apple.com/documentation/mailkit) (Apple Developer Documentation)
- [Install and uninstall apps from the internet or a disc on Mac](https://support.apple.com/guide/mac-help/install-and-uninstall-apps-from-the-internet-or-disc-mh35835/mac) (Apple Support)

## Frequently asked questions

### What is the "Bundles (Disabled)" folder next to Bundles?

When an older version of Mail found a plug-in it couldn't load, it moved it into a sibling folder named Bundles (Disabled), sometimes with a number added. Those copies were already switched off, so they're leftovers too.

### Will removing a bundle delete any of my email?

No. Messages, mailboxes and account settings live elsewhere in ~/Library/Mail and in your mail accounts. A .mailbundle only contains plug-in code and resources.

### Why does Terminal say "Operation not permitted" when I list ~/Library/Mail?

macOS protects the Mail folder. Terminal needs Full Disk Access in System Settings → Privacy & Security before commands like ls or du can read it. Finder can still open the folder for you.

---

Canonical page: https://fresh.ist/library/mail-bundles/
Official site: https://fresh.ist/ (fresh.ist only)
Generated: 2026-10-10