Whether you are backing up years of email before a repair, moving to a new Mac, or archiving an old account, the Mail app on your Mac can save any mailbox as a portable .mbox file and read it back later. Attachments come along inside the file — nothing is left behind. Here is the exact process for both directions.
Export a mailbox to a .mbox file
- Open the Mail app on your Mac.
- In the sidebar, select one or more mailboxes you want to save. To pick several at once, hold Command and click each one.
- In the menu bar, choose Mailbox > Export Mailbox.
- Choose an existing folder or create a new one (your Desktop or an external drive both work), then click Choose.
Mail writes each mailbox as its own .mbox package. If you have exported that mailbox before, Mail does not overwrite the old file — it creates a new one such as My Mailbox 3.mbox, so you never accidentally lose a previous backup.
Import a mailbox from a .mbox file
- Open the Mail app.
- Choose File > Import Mailboxes.
- Pick the correct source, read the note that appears, then click Continue:
- Choose Apple Mail if the file was exported from Mail, or is a folder from
~/Library/Mail/on another Mac. - Choose Files in mbox format if the messages came from a Windows or UNIX mail program, then point Mail at the folder containing them.
- Choose Apple Mail if the file was exported from Mail, or is a folder from
- Locate the folder or file, then let Mail import. Your messages land in a new mailbox called Import in the sidebar.
- Drag the messages or folders from Import into new or existing mailboxes, then delete the empty Import mailbox to tidy up.
Moving email to a new Mac
Exporting and importing is the simplest way to carry email between machines without re-downloading everything from a server — especially for On My Mac local mailboxes that do not live on an IMAP server. Export the mailboxes on the old Mac, copy the .mbox files across (AirDrop, a USB drive, or a shared folder), then import on the new one.
If you are setting up a whole new machine, it is usually faster to move everything at once with Migration Assistant — see our guide on how to move data from an old Mac to a new Mac. Use the export/import method when you only want specific mailboxes, or when the two Macs are not in front of each other at the same time.
Where Mail keeps your mailboxes
If you would rather grab the raw files, they live in a hidden Library folder. Click the desktop to switch to the Finder, hold the Option key, choose Go > Library, then open the Mail folder. Copy the whole folder to back it up, but use Export/Import for anything you plan to reopen in Mail — it keeps the message structure clean.
Frequently asked questions
Are attachments included in an exported mailbox?
Yes. A .mbox file stores the full messages and their attachments together. People sometimes think attachments are missing because they do not see them until they open a message inside the imported Import mailbox — they are there.
Can I open a .mbox file exported from another email app?
Usually yes. Standard mbox files from Thunderbird, Windows, or UNIX mail programs import through the Files in mbox format option. Proprietary formats (like Outlook's .pst) need to be converted to mbox first.
Will importing create duplicate emails?
Imported messages always arrive in a separate Import mailbox rather than merging into your inbox, so you can review them before moving anything. If you drag a message into a mailbox that already has it, Mail keeps both copies — it does not automatically de-duplicate.
My mailboxes disappeared from the sidebar — where did they go?
Choose View > Show Mailbox List, or click Mailboxes in the Favorites bar, to bring the list back.
More Mail on Mac guides
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