How to clear Mail cache on Mac
To clear Mail cache on Mac, it helps to know that Apple Mail has no single cache folder: the space it takes is mostly the copies of your messages and attachments it keeps for reading offline. This guide shows how to see how much that is and shrink it without losing the mail you keep, from erasing deleted mail to removing old accounts.
How much space does Mail take?
- Choose Apple menu › System Settings, click General in the sidebar, then Storage.
- Wait while the list loads and find Mail: it shows how much your emails and attachments take on this Mac.
Don’t clean Mail’s folders in your Library by hand. They hold your messages, and mailboxes under On My Mac exist only there.
Clear Mail cache: big messages and deleted mail
- In Mail, choose View › Sort By › Size to find the largest messages, then delete the ones you don’t need.
- Choose Mailbox › Erase Deleted Items and pick an account, to remove what is in the Trash for good.
- Choose Mailbox › Erase Junk Mail.
To do this automatically, choose Mail › Settings › Accounts, select an account, click Mailbox Behaviors and choose when to erase deleted messages.
Attachments: what Mail downloads and keeps
- Mail › Settings › General › Remove unedited downloads: attachments you open are kept in a hidden Mail Downloads folder in your Library. By default, one you haven’t edited or saved is deleted when you delete its message.
- Mail › Settings › Accounts › Account Information › Download Attachments: Recent downloads only attachments from the past 15 months, None downloads none. Images, PDFs, video and audio are always downloaded.
- Attachments you save go to your Downloads folder, and Mail never deletes them: see how to delete downloads on Mac.
Message › Remove Attachments strips the files from a message and keeps its text. On IMAP accounts this also deletes them from the mail server, and they can’t be retrieved: save the ones you need first.
Rebuild a mailbox
Rebuilding is for a mailbox where messages look missing or garbled, or search doesn’t find them. For IMAP and Exchange accounts, Mail deletes the messages and attachments stored on your Mac and downloads them again from the server. The mailbox looks empty until that finishes.
- In the Mail sidebar, select a mailbox.
- Choose Mailbox › Rebuild.
- Repeat for each mailbox that misbehaves. A big mailbox can take a long time.
Remove the data of accounts you no longer use
When you remove an account, its messages are removed from your Mac. Copies stay on the mail server. If you aren’t sure the server still has the messages you need, first move or copy them to a mailbox under On My Mac.
- Choose Mail › Settings, then click Accounts.
- Select the account and click the Remove button (−).
- If Mail says other apps use the account, open System Settings › Internet Accounts, select it and turn Mail off.
Keep your Mac tidy
MacWashing leaves Mail’s messages and attachments untouched: use Mail’s own tools above, they know what is still on the server. System Junk in MacWashing clears the caches of your other apps.
Free trial · macOS 14 or later
Questions and answers
Will clearing Mail cache delete my emails?
The steps here don’t touch messages you keep. Erase Deleted Items removes only what is already in the Trash, and Rebuild downloads IMAP and Exchange mail again from the server. Be careful with Remove Attachments: on IMAP accounts it deletes the files from the server too.
Where does Mail keep attachments?
Attachments you save go to your Downloads folder. Ones you only open stay in a hidden Mail Downloads folder in your Library and, by default, go away when you delete the message.
Why does Mail take so much space?
Mail keeps a copy of your messages and their attachments on the Mac so you can read and search them offline. Years of mail with photos and PDFs easily reach many gigabytes.