Apple Mail not working? Rebuild the mailbox & fix it fast

Apple Mail usually works reliably, but sometimes things go wrong. You may notice that new emails take a long time to arrive, search stops finding messages, emails disappear, or the Mail app becomes slow.

These issues are often caused by problems with your mailbox or Mail search. Fortunately, they're usually easy to fix. Rebuilding refreshes your mailbox, while reindexing fixes Mail's search database.

In this guide, we'll explain when you should rebuild your mailbox, when you need to reindex Apple Mail instead, and show you how to do both step by step.

First things first

Before getting started with rebuilding and reindexing your Mailbox, you’ll want to tidy up Apple Mail:

• Delete messages you no longer need
• Delete all messages in your Deleted Items and Spam folders
• Update to the latest version of Mail

Now that some housekeeping is out of the way, you’ll have a clean slate to work with.

Which fix do I need?

Use this quick guide to decide which solution fits your problem:

Rebuild the Mailbox on your Mac

You may be thinking: “Re-build a mailbox? I don’t even know how to build one in the first place!” But don’t sweat: it’s actually pretty easy. 

When you rebuild a mailbox, the copies of your emails stored on your Mac are deleted, then downloaded again from your mail server.

Here’s how to do it:

1. Open Mail.

You can do this either by clicking the Mail icon (if it’s in your dock) or using Spotlight search (press Command + Space to open Spotlight) to locate the app.

2. Select the Mailbox you’d like to rebuild from the sidebar on the left. 

If you can’t see this sidebar, click on View in the Menu Bar and select Show Mailbox List from the drop-down menu. You can also show or hide your Mailboxes with the keyboard shortcut Shift + Command + M.

3. Select Mailbox from the Menu Bar and click Rebuild.

You’ll have to repeat this step for each of your Mailboxes. Additionally, if you have a larger mailbox with a lot of messages, you can expect this process to take longer (up to a few hours).

What if rebuilding the mailbox gets stuck?

If rebuilding doesn't finish or Mail freezes during the process, try these steps:

• Restart your Mac and try again.
• Start your Mac in Safe Mode and rebuild the mailbox.
• If you're rebuilding a very large mailbox, allow more time—the process can take several hours.
• If the problem continues, try manually reindexing Apple Mail using the steps below.

Reindex your Apple Mailbox

Rebuilding your Mailboxes is often enough to solve many of the issues an overburdened Mail app may experience. However, if you’re still having problems (such as the app becoming so unresponsive it barely works or fails to open), you should manually reindex your Mailboxes.

Here’s how to manually reindex your Mailbox:

1. First, quit Apple Mail if the app is running.
2. Open the Finder and select Go from the Menu Bar.
3. Enter ~/Library/Mail/ and press Return.
4. Choose the V10 folder (depending on your macOS version, it can be named V5, V6, or V7) > MailData. Next, locate and delete all the files that start with Envelope Index, such as “Envelope Index” or “Envelope Index-wal.” 

Note: It’s a good idea to copy each file to your desktop before deleting it.



5. Open Apple Mail. Next time you open Mail, it will build entirely new Envelope Index files. You may have to be patient—this process can take a while if you have a lot of messages for Mail to go through.
   

Now, everything should be working as normal! If so, you can get rid of the Envelope Index file copies from your desktop.

Refresh your Mail and fix errors

This is the final tip, and it’s a pretty easy one because this time, we’ll use an automatic tool.

A popular Mac app you’ve probably heard of, CleanMyMac, has a dedicated tool to fix Mail errors. 

1. Start your CleanMyMac trial (free for 7 days).
2. Open the app and go to the Performance tab.
3. Click Scan > View All Tasks > Speed Up Mail.
4. Click Run.

This will speed up Mail search and reindex mailboxes. 

• Delete old Mail attachments

While you are in CleanMyMac, there is another useful thing you can do. Each time you view an attachment in Apple Mail, the app saves a copy of the file to your Mac. This can take up lots of much-needed space.



You can use the Cleanup tool to clean up the images, PDFs, or even company logos that your Mail app has saved. It even smart-selects for removal only attachments that can easily be brought back by accessing the emails they originated from. Additionally, if you’ve made changes to your attachments, CleanMyMac marks them as User-Modified and won’t select them for removal.

You can get a free trial of CleanMyMac here. Hope you’ve successfully fixed your Mail with these tips. 

Frequently asked questions

Will rebuilding my mailbox delete my emails?

Usually, no. Rebuilding refreshes the copies of your emails stored on your Mac instead of deleting your messages. However, if you keep emails that exist only on your Mac, it's a good idea to back them up before rebuilding, just to be safe.

How long does it take to rebuild a mailbox on Mac?

It depends on the size of your mailbox. Smaller mailboxes usually rebuild within a few minutes, and larger ones with thousands of messages can take much longer — sometimes several hours. During this time, Mail may appear busy while it downloads and indexes your emails.

What's the difference between rebuilding and reindexing Apple Mail?

Rebuilding refreshes the local copies of your emails by downloading them again from your mail server. Reindexing recreates Mail's search database, which helps fix problems such as search not finding emails. If you're unsure which to use, rebuild the mailbox first, then reindex Mail if the issue remains.

What is the Envelope Index in Apple Mail?

The Envelope Index is Apple's local search database for Mail. If it becomes corrupted, Mail may stop finding emails even though they're still on your Mac or mail server. Deleting the Envelope Index files doesn't remove your emails, it just forces Mail to create a fresh search index the next time you open the app.