How to Stop Your Mac’s Mail App From Wasting Gigabytes of Space

By Chris Hoffman on February 20th, 2015

Are you using Apple’s Mail app on your Mac? Then you’re losing gigabytes of space you could be putting to better use! The mail app wants to cache every single email and attachment you’ve ever received offline.

This could take up tens of gigabytes of space if you have a lot of emails. On a Mac with a large hard drive, this isn’t a big deal. But, on a MacBook with 128 GB of solid-state drive space, this can be a significant waste of space.

Check How Much Space Mail is Using

Each user account on your Mac has a Mail directory in their Library folder — that’s ~/Library/Mail, or /Users/NAME/Library/Mail. This is where the Mail app stores its data for each user.

Open Finder, click the Go menu, and select Go to Folder. Type ~/Library into the box and press Enter. Locate the Mail folder, right-click or Control-click it, and select Get Info. You’ll see how much space is being used by the Mail app for your user account.

Option 1: Clean Up Mail Attachments Using CleanMyMac

The biggest thing that takes up a ton of space in your mailbox is all the attachments that come through, many of which aren’t very important.

There aren’t a lot of options for deleting your mail attachments from the local copy while leaving them on the server, but thankfully there is a piece of software that does this. CleanMyMac 3 has a tool that will look through your email and find the large attachments and assuming you are using IMAP (which is the default), it will leave the attachments on the server and only delete the local copy.

It’s worth noting that CleanMyMac 3 has a ton of other tools to help you clean up your Mac and free up some disk space, so if you are trying to figure out how to free up some disk space, it can definitely help you.

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You should just definitely use the “Review Details” button to look through and make sure you’re only removing stuff you won’t need locally. And it’s not a bad idea to have backups of your most important stuff before deleting anything.

Option 2: Reduce the Space Mail.app Uses

The Mail folder grows so large because the Mail app downloads every single email and attachment to store them on your Mac. This makes them accessible entirely offline and allow Spotlight to index them for easy search. However, if you have gigabytes of emails in your Gmail account or elsewhere, you may not want them all on your Mac!

There was once a way to control the size of the email cache by changing the “Keep copies of messages for offline viewing” option to “Don’t keep.” This option was removed in OS X Mavericks, so there’s no longer any way to tell Mail to download less messages from within Mail itself.

However, you can save some space by telling Mail not to automatically download attachments. Open the Mail app, click the Mail menu, and select Preferences. Click the Accounts icon and select the account you want to change settings for. Click the Advanced tab and uncheck the “Automatically download all attachments” option. Attachments won’t be automatically downloaded, but will be stored online until you use them — that’ll save some space.

Failing this, you can only hope to control the amount of messages Mail downloads via server settings on your email server. For example, Gmail offers a setting that can “hide” emails from the Mail app and other email client that access it over IMAP.

To access this setting, open Gmail in your web interface, click the gear menu, select Settings, and click the Forwarding and POP/IMAP tab — or just click here. Under Folder Size Limits, you can select an option to the right of “Limit IMAP folders to contain no more than this many messages.” This will prevent the Mail app from seeing and downloading all your mail.

Other email services may have similar options.

You could also theoretically stop Mail from using IMAP and rig it up to use POP3 and SMTP to receive and send emails. You could then delete mails from your Mail app and they’d be deleted on your computer, but not on your email server. POP3 really isn’t ideal for a modern email system, but this would give you email notifications with Mail and allow you to send messages from it while leaving your archive solely on your email server.

Option 3: Ditch Mail and Use Something Else

There’s no way to disable this space-wasting behavior completely, so you may just want to stop using the Mail app. Then you can delete those gigabytes of locally cached data and Mail won’t try to download any more emails. Instead of the Mail app, you can use your email service’s web-baesd interface — Gmail on the web for Gmail users, for example. You could also look for a third-party email client on the Mac App Store or elsewhere. Other email clients should offer an option to store less emails offline and limit the size of our cache to a manageable size.

To stop using the Mail app, first disable or delete your email accounts. Click the Mail menu in Mail and select Accounts. Uncheck the Mail option for accounts you no longer want to use Mail with. Mail will stop downloading emails from those accounts.

But this isn’t enough! Disable the email account and the emails will no longer appear in the Mail app, but they’re still stored in your offline cache. You can delete the folder to free up the space.

Open Finder, click the Go menu, and select Go to Folder. Plug ~/Library/Mail/V2 into the box and press Enter. Right-click or Control-click the folder with the name of your email account and select Move to Trash. You can then empty your trash to free up all those gigabytes.

If you have multiple email accounts with cached emails you want to remove, you should delete each corresponding folder. You’ll lose all the offline copies of your mail if you do this, but it’ll still be stored on your email server if you use a modern email service.


Other people have their own tricks. Some people reccomend creating a separate email account you use to archive emails. Forward all your emails there and then delete them from the “working” email account you keep in Mail to save space when you no longer need them. But that’s a dirty hack of a solution, and is only necessary because Apple removed a useful option from the Mail app. if you’re that desperate, you may just want to use a different email client instead.

Chris Hoffman is a technology writer and all-around computer geek. He's as at home using the Linux terminal as he is digging into the Windows registry. Connect with him on Google+.

  • Published 02/20/15

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