What to Do When Apple Mail App is Very Slow on Mac

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Nothing much besides bills and magazines comes by snail mail these days, unlike your ever-overflowing email inbox.

But sometimes the world of electronic mail isn’t nearly as swift as we’ve come to expect it to be — and that creates problems when all you want to do is send that last email to your boss or professor so you can get on with your life.

Apple Mail app running slow on a Mac

Apple Mail app running slow on a Mac machine is both unexpected and unwanted. After all, you want to be able to use Apple’s flagship laptops with their custom-built applications rather than trying to work with a secondhand program that doesn’t have the features you’re used to.

That’s why we’ve compiled this guide, which will point you to the easiest ways to get Mail running as it should in no time. All of them are fairly universal, and if one doesn’t seem to do the trick, you should be able to try another with ease.

1. Force Quit Mail

Has the pinwheel of death appeared on your screen? It’s a fate we all know too well — whether you just pressed send or didn’t have a chance after typing an extra-long message, the loading wheel always seems to show up at the most inopportune time. If waiting it out doesn’t seem to be a possibility, it’s time to circumvent this technological curse.

First, navigate out of the Mail app (clicking Finder in the dock is a good bet). Then go the Apple Menu in the top left corner of your screen and choose ‘Force Quit’.

Force Quit Mail

This will open a small window listing all of your open applications. You’ll want to select Mail (it may have the words “(not responding)” in red next to it, which is just an indicator that it has crashed. Once you’ve selected Mail, click the button that says “Force Quit”. You may be asked to confirm your action.

 select Mail
Force Quit

Give Mail a few moments to be terminated before you relaunch the app. However, once you reopen it everything should be back in working order.

At worst, you’ll lose the draft of whatever message you were working on when you closed it, but beyond that, there should be no effect on functionality. In fact, you should see Mail app run faster and more efficiently than before.

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2. Rebuild the Message Index Database

Does Mail seem to be lagging on tasks that used to be completed in just a second or two? Especially if you have a lot of contacts in your address book or have stored a lot of messages, you can rebuild the Message Index Database to help Mail get back on its feet. This will take some time, but it will definitely be worth it.

Rebuilding the database essentially restructures the catalog of all your messages and contacts, which allows the app to access them more efficiently and thus reduce loading and other process times. For the best results, try and do this regularly rather than waiting until Mail is showing signs of needing it.

First, open the Mail App. Then in the menu bar navigate to Mailbox > Rebuild.

Navigate to Mailbox > Rebuild

You can quit Mail in the middle of the process without worrying about losing any messages or progress — the rebuilding process will simply pick up where it left off when Mail is reopened.

Also, keep in mind this only rebuilds the current mailbox, so if you’re using more than one you’ll need to rebuild them each individually.

3. Speed up Mail with This App in One Click

CleanMyMac X is an awesome Mac cleaner app that we have referenced many times due to its amazing versatility and effectiveness. It once again comes in handy for the case of a painfully slow Mail app.

You’ll need to get a copy of the app first. Once it’s installed and running, you’ll want to navigate to the Maintenance tab. Once there, choose the Speed Up Mail option by checking the box and then clicking “run” at the bottom of the page.

 Speed up Mail

If you are using CleanMyMac for the first time, the Speed up Mail feature requires you to grant access. Just hit the “Grant Access” button and follow the instructions to add CleanMyMac to the list.

Speed up Mail feature requires you to grant access

You can also select any additional processes you’d like to execute to speed things up at the same time by clicking the relevant checkboxes.

The program shouldn’t take too long to run, and you’ll see a brief loading screen while you wait. Once it’s over, you’ll be presented with a completion screen so that you know everything is done and Mail is ready for use again.

This is a super effective and simple way of making sure Mail doesn’t have any tricks up its sleeve, and it comes with the added benefit of dozens upon dozens of other tools.

Not only will your emails load and send faster, but you can make your entire Mac operate a little speedier with everything from easy application uninstallation to everyday maintenance tasks that are difficult to do by hand.

4. Turn Off Mail Preview

Mail preview can slow down the Mail app, especially if you have many messages with a lot of information. The app automatically previews messages from your inbox, convenient when you are scanning through but not always necessary – especially if it causes some performance issues.

To turn off Mail preview, all you need to do is position your cursor near the vertical line that separates the message list from the preview window. It will change from the standard arrow into a slider arrow. You can then click and drag the pane all the way to the right and get rid of mail preview.  

5. Check Your Internet Connection 

It’s always good to start with the basics with any tech problem, so if your Mail app is running slow, you can always double-check your internet connection to make sure that you have a good signal and aren’t experiencing issues within the app itself. 

Click on the internet or wireless signal icon from the top of your Finder window to check for a connection. You will see a list of available networks, and each will have signal strength displayed.

Make sure you are connected to the proper network and that it has a signal. Switch to another network or check your modem or wireless source if not. 

Also Read: How to Fix Wi-Fi Issues on MacBook Pro

6. Remove Your User And Add It Back 

Another fix you can attempt to speed up your mail app is to remove your user name and then add it back. This is kind of like a restart within the app itself and can improve slow performance. 

To remove your user from the mail app, follow these steps:

  1. Open the Mail app
  2. Click on Mail from the top of the window
  3. Click on Preferences
  4. Click on Accounts
  5. Select the account you want to remove and click Remove

To add your user back to the mail app, follow these steps:

  1. Open the Mail app
  2. Click on Mail from the top of the window
  3. Click Add Account
  4. Follow the steps to connect through your email provider

 7. Restart your Mac

Restarting your Mac is a go-to fix for many common problems and is always a good place to start. A simple restart can fix many issues that seem weird or that you can’t fully figure out. Call it the ghost in the machine or whatever you’d like, but when in doubt – simply restart. 

The easiest way to restart your Mac is to click on the Apple icon on the top left of your screen and then select Restart from the drop-down menu. Your computer should restart in a minute or less, but you might need to close any open programs that are preventing it from doing so. 

Restart your Mac

If the mail app is slow and nothing else is working, restart and see if that fixes it.

Final Words

It’s never fun when Apple Mail runs slow on your Mac. Whether you’re drafting an email to your boss or simply sorting through spam and old messages, the hindrance interferes with your productivity and can derail your work.

Additionally, it’s nice to be able to use the programs Apple intended for the computers rather than resorting to checking your mail in an ad-ridden browser window or with a less effective third-party application.

We hope the tactics included in this guide help prevent this from happening in the future and solve any problems you may currently have.

Do you have your own way of speeding up Mail when it starts to slow? Feel free to tell us about it in the comments below!

About Lorena
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Lorena holds a 13-inch Touch Bar MacBook Pro with Apple M1 Chip. Her role involves editorial management from writing to editing and ensuring that the articles are informative, useful, and relevant to readers who are new to Mac.

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  • Avatar


    I’ve bought a copy of CleanMyMac on the strength of this article. It has done a good general clean up job but there is no longer a Speed Up Mail
    Actually, i’ve just found it under Maintenance and then Run Scripts!

  • Avatar

    Gary Laevsky

    Restarting in Safe Mode fixed it for me!

  • Avatar


    I can’t find the Speed Up Mail in my CleanMyMacX.

  • Avatar

    Ted Lane

    I use CleanMyMac X (full version) but the Speed Up Mail consistently fails. The app works fine for other functions including Smart Cleanup.

    • macbookproslow logo


      Hi Ted, can you show us the failure message if you have? Thanks!