How to clear Mail storage on Mac

The default macOS Mail app is an invisible space eater. It keeps you in the dark about the actual storage it uses and if left unchecked, Mail app may silently grow to an enormous size. But here we'll try to trim down its size. You'll see how easy it is.

How to check the space Mail is taking up

Before you do anything, let’s investigate how serious your storage problem is. The storage Mail occupies consists of two parts: the Mail app itself and your user-created data.

Open the Apple menu > About this Mac > Storage > Manage.
Choose Mail in the sidebar.

Delete Mail Storage on Mac

Now I know that my Mail takes up 724 MB of storage. But that's far from true and doesn't take into account your downloaded messages and attachments. Hence, to delete Mail storage on Mac, the easiest is to start with Mail attachments and junk mail.

Mail attachments

Mail Attachments can either remain on the server or be downloaded to your Mac, depending on the type of file and the option you specify in Account Preferences. For example, images, PDFs, video, and audio files are always downloaded, and they’re displayed in the body of the email. You can choose whether other types of files are downloaded by doing the following:

Attachments can either remain on the server or be downloaded to your Mac
  1. Launch Mail.
  2. Click the Mail menu and choose Preferences.
  3. Select the Accounts button and the Account Information tab.
  4. Choose an option next to Download Attachments.

Whether you download attachments or leave them on your mail server, they take up space somewhere. And if you get lots of attachments that can mean occupying quite a bit of space. Remember, it’s not just documents, PDFs and photos that are sent as attachments, company logos and other images in email signatures are attachments too. The solution is to delete those you no longer need, perhaps after archiving them if you think you may need them in the future.

How to delete Mail attachments in messages

How to delete Mail attachments in messages
  1. In Mail, locate the message which has the attachment you want to delete. If you’re having trouble finding messages with attachments, you can click the View menu and then Sort by > attachments.
  2. Click on the message.
  3. Select the Message menu in the menu bar and choose Remove attachment.
  4. Repeat for every message whose attachment you want to delete.

You can remove attachments from multiple messages at the same time, by shift-clicking on messages to select them and then choosing Message> Remove attachment. If you want to remove all the messages with attachments, as well as the attachments themselves, you can select all the messages that have attachments in one go and delete them.

How to archive attachments before you delete them

  1. Repeat steps 1 and 2 above.
  2. Move the mouse pointer to the line above the body of the message and you’ll see five icons: trash, reply, reply all, forward, and attachment.
  3. Click on the attachment icon and choose Download All.
  4. Choose a location to save the attachment and select Save.

How to remove attachments from your Mac in one go

Recent versions of macOS have a feature that allows you to optimize storage space on your Mac. One of the ways in which it does this is to remove Mail attachments. Here’s how to use it.

  1. Click on the Apple menu and choose About this Mac.
  2. Choose the Storage tab and then press Manage.
  3. Click on Mail in the left hand sidebar. Underneath, you’ll see how much space attachments are currently occupying.
  4. Select attachments and press Delete.
remove attachments from your Mac in one go

How to manually remove Mac Mail attachments in Finder

If you’re running a version of macOS that doesn’t have the Optimize storage feature, and have too many attachments to remove one message at a time, there is another way. Mail stores attachments you’ve downloaded in your Library folder. You can locate them and drag them to the Trash to free up space. However, that will only delete those you’ve downloaded and free up space on your Mac, it won’t remove them from your email provider’s server. Here’s how to find and remove them.

  1. Click on the Finder icon in the Dock.
  2. Choose the Go menu and click Go to Folder.
  3. In the text box, type the following: “~/Library/Containers/ Downloads/“
  4. Press Go.
manually remove Mac Mail attachments in Finder

A Finder window will open at that location, showing you the contents of the Mail Downloads folder. Inside Mail Downloads are lots of other folders. And inside those folders are the attachments you’ve downloaded. To find out what’s inside each folder, you’ll have to open it. However, if you just want to delete everything Mail has downloaded, you can drag all the folders to the Trash.

That’s not the only place Mail stores attachments, however. There are also attachments in ~/Library/Mail/V6. Again, there are lots of sub-folders inside the V6 folder, and some of them contain mailboxes. Some of those mailboxes have attachments folders in them. Tracking down attachments this way could take hours, or even longer.

How to remove attachments from Mail the easy way

If you want to free up space used by Mail quickly and easily and delete attachments in bulk without having to locate them in Finder, there is an easier way. CleanMyMac X has a utility specially designed to remove Mail attachments.

  1. Download CleanMyMac X and then launch it.
  2. Click on Mail attachments tab.
  3. Press Scan.
  4. Click Clean to remove them at once.
  5. If you’d prefer to look over the attachments before deleting them, scroll through the list of attachments and uncheck the box next to any you want to keep.
  6. Press Clean.
CleanMyMac X - Mail Attachments module

CleanMyMac can also delete attachments from third-party email clients, like Outlook and Spark. Therefore, if you use these email apps, you can easily locate unneeded attachments and delete them in a few clicks. With the help of CleanMyMac X, you can also scan your Mac for other junk files, malware threats, and speed up your machine. All that in a few clicks.

Attachments in Mail can occupy several gigabytes of disk space on your Mac. Manually removing them to free up space can be a long and laborious process. If you do decide to use a manual method, deleting them from within Mail is the safest option. However, it’s much easier to use CleanMyMac X to do the job. And remember, even if you delete attachments on your Mac, if you use an IMAP account like iCloud mail or Gmail, your attachments will remain on the server and can be retrieved when you need them.

How to reduce the space taken by

There are few final tips to help you clear Mail storage on Mac.

Delete Junk Mail and Deleted items

    • Open Mail and choose the Mailbox in the upper menu.
    • You’ll see two options: Erase Deleted Items and Junk Mail.                   

    This will clear up some portion of Mail storage.

    Clear Mail Storage on Mac

    Look inside your Mail folder

    While it's generally not recommended to mess with the inner contents of Mail in Library, you can at least go there and look for any suspiciously large objects. 

    Open Finder > Go > Go to Folder...
    Paste in the following combination: Library/Containers/ Data

    Examine the contents of that directory and double-check any items you plan to delete. This is how you clear Mail storage on Mac.

    Laptop with CleanMyMac
    CleanMyMac X

    Your Mac. As good as new.