What are EML and MBOX?

Our Proton Export Tool and Proton Mail Bridge allow you to export your messages in EML and MBOX formats for various use-cases. You can also import messages locally stored EML or MBOX files using Bridge.

When you export emails, you have the option to download the files as EML or MBOX. The main difference is that the MBOX format exports each folder as a separate file, while EML exports each email as a separate file.

Most email clients, including Outlook, Thunderbird, and Apple Mail, support both EML and MBOX. You can also use some text editors, such as TextEdit, to open and view EML files.

If you want to export several messages from your account but not a whole folder or mailbox, we recommend exporting your files in the EML format.

If you want to export your mailbox or a whole folder, or you want to make a backup of your messages, you can export your files in MBOX format.

When you export emails, they are decrypted so that you can view them in other email clients or applications. When you import emails to Proton Mail, they are immediately encrypted with your PGP key.