Mac storage basics · Mail, Messages and chat apps
Why is Apple Mail using so much space on my Mac?
Short answer: Mail stores local copies of messages and attachments, plus opened attachments in Mail Downloads. Delete big old messages, erase deleted items, and limit attachment downloads.
Mail keeps a local copy of your messages and, depending on settings, their attachments, so large or long-lived accounts add up. Attachments you've opened are also saved in a separate Mail Downloads folder.
Ways to shrink it:
- Delete large old messages, then Mailbox → Erase Deleted Items.
- Limit attachment downloads for IMAP accounts (see attachments setting).
- Remove accounts you no longer use from the Mac.
- Clear old files from Mail Downloads.
Storage Studio's What's Using Space shows the Mail library's size and the Mail Downloads leftovers separately.