How to Clear Apple Mail Storage (7 Easy Methods)

Is Mac storage filling up quickly? Apple Mail is one of the biggest reasons. If you use Apple Mail regularly on your Mac, iPhone, or iPad, you may notice that the Mail app starts consuming a large amount of storage. Apple Mail takes up several gigabytes of space, especially as attachments, cached messages, and archived emails grow over time.

To tackle this situation, today, I’ll explain how to clear Apple Mail storage step-by-step, and the safest ways to reduce the storage used by Apple Mail without losing important emails.

Why Does Apple Mail Take Up So Much Storage

Before learning how to clean up Apple Mail storage, I want to answer one question which is asked by most of the users, i.e. why does Apple Mail take up so much storage? Managing multiple mail accounts, the storage usually increases because of:

• Downloaded attachments (PDFs, images, documents)
• Offline email copies are stored on the device
• Mail cache files
• Large archived folders
• Deleted emails are still stored in the Trash
• Multiple email accounts syncing locally

Even if your mailbox is stored in the cloud, like iCloud, Gmail, or Outlook, Apple Mail keeps local copies of messages and attachments to allow offline access. Understanding why does Apple Mail take up so much storage helps you identify the exact areas that need cleanup.

Also read: Apple Mail Messages Stuck in Outbox

Take a Backup Before Clearing Apple Mail Storage

Before you begin learning how to clear Apple Mail storage, always back up Apple Mail to an external hard drive or local storage. This step ensures data continuity, especially if some emails or attachments are accidentally removed during the cleanup process. 

In many organisations and professional environments, emails contain critical business communication, invoices, and attachments. Once deleted, recovering them can be difficult or even impossible. That’s why I always recommend creating a backup before attempting how to delete Apple Mail storage files or performing mailbox cleanup.

One reliable solution I have used is the SysTools IMAP Backup Tool, which allows me to securely back up IMAP-based mailboxes such as Gmail, Yahoo, Outlook, and other hosted email services before performing how to clean up Apple Mail storage operations.

For Windows For macOS Purchase Now

Why Take a Backup First?

Ensure that you have a full copy of your emails so that:

• Important emails remain safe and accessible
• Attachments are preserved for future reference
• Restore emails if anything is deleted accidentally
• Maintain data continuity during mailbox maintenance

This approach is especially useful when Apple Mail storage is large and requires bulk cleanup of attachments or cached data. It allows you to safely archive your mailbox before performing how to clear Apple Mail storage cleanup operations.

Key Features of SysTools Backup Software

This tool offers several useful capabilities for email backup:

• Backup IMAP emails into PST, MBOX, EML, MSG, or PDF formats
• Supports multiple email services that use IMAP
• Allows selective email backup using date filters
• Preserves email metadata and folder hierarchy
• Option to incrementally back up new emails

These features make it easier to create a complete offline archive of emails before clearing Apple Mail storage.

Although there are some manual ways available to back up Apple Mail data, I don’t recommend using them, especially when the mailbox contains a large number of emails and attachments. In my experience, manual methods can be time-consuming and difficult to manage. Moreover, they come with fewer export options and no easy way to perform selective or incremental backups. 

Because of these limitations, managing a complete and reliable backup manually can become complicated, which is why many users prefer to opt for a professional, specified approach to ensure 0% data loss chances.

Related guide: Migrate Apple Mail to Gmail

How to Clear Apple Mail Storage Step by Step

As per my experience, there are seven tried and tested approaches which can help to clean up the complete Mac Mail mailbox simultaneously. If you ensure you have a backup of your complete mailbox, then only move to the next section for the cleanup procedure without any ifs or buts:

Method 1. Delete Large Attachments from Apple Mail

One of the quickest ways to reduce Apple Mail storage is by removing large email attachments. If you properly take a complete backup with attachments, then follow these steps:

1. Open Apple Mail on your Mac.
2. Click the View menu.
3. Select Sort By > Attachments.
4. Look for emails with large files.
5. Open the message and remove or download the attachment.
6. Delete the email if it’s no longer needed.

Alternative Approach

You can also search for emails with attachments:

1. Open Mail.
2. In the search bar, type:

Attachments

1. Review the results.
2. Delete unnecessary emails with large files.

Attachments such as videos, PDFs, and presentations will fill the Mail storage with several gigabytes.

Method 2. Empty the Mail Trash and Junk Folders

Many users forget or don’t even know that deleted emails remain in the Trash folder and occupy space. Whenever you delete any email or attachments, ensure to clear them from the trash folder also. To do so:

1. Open Apple Mail.
2. Select Trash in the sidebar.
3. Click Mailbox > Erase Deleted Items.
4. Confirm the action.

Now repeat the same for Junk Mail:

• Click Mailbox > Erase Junk Mail.

This immediately clears storage used by deleted emails. Doing this periodically, or monthly, will help you to save from the Apple Mail storage limit exceeded issue and simplest ways to perform how to clear Apple Mail storage.

Method 3. Remove Downloaded Attachments from the Mail Downloads Folder

Apple Mail automatically stores attachments in the Mail Downloads folder, which can grow quickly. For the same:

1. Open Finder.
2. Navigate to:

~/Library/Containers/com.apple.mail/Data/Library/Mail Downloads

1. Review the files.
2. Delete unnecessary attachments.

If you don’t need offline copies of attachments, removing them can free up hundreds of megabytes or even several gigabytes.

Method 4. Rebuild Mailbox to Remove Cached Data

Apple Mail stores temporary cache files that can increase storage usage. Rebuilding the mailbox forces Apple Mail to re-download messages from the server and remove unnecessary cache files. To do so:

1. Open Apple Mail.
2. Select the mailbox you want to rebuild.
3. Click Mailbox in the top menu.
4. Choose Rebuild.

Use this method when:

• Mail search stops working
• Storage usage becomes unusually large
• Mailboxes appear duplicated

Rebuilding is an effective way to perform how to clear Apple Mail storage cache data safely.

Method 5. Delete and Re-Add the Mail Account

If Apple Mail storage remains extremely large, sometimes resetting the mailbox completely works. Don’t worry, removing the mail account doesn’t affect your mailbox data, as your emails are available on the server. Reading the account ensures all the data will be synced automatically.

This method removes all locally stored mail data and downloads fresh copies from the mail server. Here’s how:

1. Open System Settings.
2. Click Internet Accounts.
3. Select your email account.
4. Disable Mail or remove the account.
5. Restart your Mac.
6. Add the email account again.

This process removes all locally stored data and downloads fresh copies from the server, effectively helping how to clear Apple Mail storage.

Method 6. Delete Apple Mail Cache Files Manually

For a deeper cleanup, remove Apple Mail cache files manually. For the same:

1. Open Finder.
2. Click Go > Go to Folder.
3. Enter:

~/Library/Mail

1. Locate folders such as:

V10

V9

V8

1. Review the MailData and Attachments folders.
2. Remove unnecessary cached files.

Method 7. Disable Attachment Downloads

If you want to stop Apple Mail storage from growing again, disable automatic attachment downloads:

1. Open Mail.
2. Click Mail > Settings.
3. Go to the Accounts tab.
4. Select your email account.
5. Change attachment download settings to Recent or None.

This prevents Apple Mail from storing every attachment locally.

How to Check Apple Mail Storage Usage

To verify how much space Mail is using, check Mac storage settings. Here’s how:

1. Open Apple Menu > About This Mac.
2. Click Storage.
3. Select Mail.

This shows the exact storage used by Apple Mail, which helps you to confirm whether there is a need for cleanup or not. 

Tips to Follow to Keep Apple Mail Storage Small

Managing large mailboxes helps prevent storage issues. For the same, follow these best practices:

• Regularly delete old emails with attachments
• Empty the Trash and Junk folders weekly
• Avoid downloading unnecessary attachments
• Archive emails instead of storing them locally
• Periodically rebuild the mailbox

Read also: IMAP Sync Issues

Author’s Verdict

Clearing Apple Mail storage doesn’t require complicated tools. You can significantly reduce storage usage simply by:

• Deleting large attachments
• Emptying Trash and Junk folders
• Rebuilding mailboxes
• Removing cached files

If Apple Mail still takes up too much space, resetting the mail account resolves the issue completely. 

By following this guide on how to clean up Apple Mail storage, you can quickly clean up Apple Mail storage and keep your Mac running smoothly. I hope you now have a clear insight into how to clear Apple Mail storage easily and quickly.

People Also Ask

• Why is Apple Mail taking up so much storage?

Apple Mail consumes large amounts of storage because it stores local copies of emails and attachments for offline access. The main reasons include:

• Large email attachments
• Cached mailbox data
• Multiple email accounts syncing locally
• Deleted emails are still stored in the Trash
• Archived emails stored on the device

2. Does deleting emails free up Apple Mail storage?

Yes, deleting emails can free up Apple Mail storage. However, I’ve noticed that the storage is only released after you permanently remove emails from the Trash folder.

If emails remain in Trash or Junk, they still occupy storage on the device.

3. How to clear Apple Mail storage on a Mac?

To clear Apple Mail storage on a Mac, follow these steps:

1. Delete emails with large attachments.
2. Empty the Trash and Junk folders.
3. Remove downloaded attachments from the Mail Downloads folder.
4. Rebuild the mailbox to remove cached data.
5. Delete unnecessary cached files from the Mail library folder.

These steps help you quickly reduce the storage used by Apple Mail without losing important messages.

4. How can I remove large attachments from Apple Mail?

When you want to reduce Apple Mail storage quickly, start by removing large attachments. To do so:

1. Open Apple Mail.
2. Search for emails with attachments.
3. Sort messages by size.
4. Delete emails containing large files such as videos or PDFs.

Attachments are the biggest contributors to Apple Mail storage usage.

5. Is it safe to delete Apple Mail cache files?

Yes, deleting Apple Mail cache files is safe if done correctly. Removing cached data free storage, and fixing Mail performance issues.

However, creating a mailbox backup before deleting any Mail system files, because incorrect deletion will cause Mail to re-download messages or temporarily affect synchronisation.

6. Will rebuilding the mailbox reduce Apple Mail storage?

Yes, rebuilding the mailbox can help reduce Apple Mail storage.

When you rebuild a mailbox, Apple Mail:

• Removes corrupted index files
• Deletes unnecessary cached data
• Re-syncs emails from the mail server

This helps fix storage issues and improves Mail performance.

7. How to prevent Apple Mail storage from increasing again?

To keep Apple Mail storage under control, follow a few simple practices:

• Regularly delete emails with large attachments
• Empty Trash and Junk folders weekly
• Avoid downloading unnecessary attachments
• Archive old emails to external storage
• Rebuild mailboxes occasionally

These habits help prevent Apple Mail from consuming excessive storage over time.

8. Should I back up my mailbox before clearing Apple Mail storage?

Yes, it is always recommended to back up your mailbox before clearing Apple Mail storage. Taking a backup ensures that important emails and attachments remain safe, even if something is accidentally deleted during cleanup.

Creating a backup allows you to confidently perform storage cleanup without risking data loss.