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EML to MBOX Converter

Combine EML files into one MBOX mailbox for import into Thunderbird, Apple Mail or other clients.

Your files never leave your device

How to convert EML to MBOX

  1. 1

    Choose your EML files

    Click the upload area or drag files onto it. Nothing is uploaded — files are opened locally.

  2. 2

    Start the conversion

    Press the convert button. Your browser converts the files in seconds.

  3. 3

    Download the result

    Download one file with everything combined, ready to save or print.

Merge many individual messages from Thunderbird, Apple Mail and webmail into a single MBOX file — the easiest way to import a batch of emails into Thunderbird or Apple Mail, or to archive them as one file.

Read the full guide with screenshots

What is EML?

EML is the standard single-email file (RFC 822/MIME) saved by Thunderbird, Apple Mail, Windows Mail and most webmail “download message” buttons. It holds the headers, body and attachments.

What is MBOX?

MBOX stores a whole mailbox — thousands of emails — in one file. Google Takeout, Thunderbird and Apple Mail exports all use it.

Is it private?

Yes. Unlike upload-based converters, ZapMorph processes files inside your browser tab, so the file stays on your device. It is never transmitted, stored or logged — close the tab and it’s gone.

Frequently asked questions

Is the eml to mbox converter free?

Yes. Convert 1 file a day without an account, or 5 files a day with a free account. Pro removes all daily limits.

Are my files uploaded to a server?

No. The conversion runs entirely in your browser, so your files never leave your device. We only count how many files you convert — never their names or contents.

What is the maximum file size?

Up to 25 MB per file without an account, 50 MB with a free account, and 1 GB on Pro. Very large files also depend on your device’s memory.

Can I convert multiple EML files at once?

Yes. Add several files and they’re combined into one document in the order you choose — 5 files on the free plan, 50 on Pro.

Does it work on Mac, Windows, iPhone and Android?

Yes. It works in any modern browser — Chrome, Edge, Firefox and Safari — on desktop and mobile, with nothing to install.

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