When you import emails to Proton Mail, they are immediately encrypted with your PGP key. When you export emails, they are decrypted so that you can view them in other email clients or applications. 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. 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. You can also use some text editors, such as TextEdit, to open and view EML files. Most email clients, including Outlook, Thunderbird, and Apple Mail, support both EML and MBOX. You need to complete the conversion in several stages like the following: Stage 1: Use Apple Mail. Mbox email client how to How to open an Mbox file in Microsoft Outlook. Apple Mail is a major email client that uses the MBOX file, but the process to convert MBOX to PST is a tricky one here. In CubeBackup, Gmail messages are exported as Mbox files (similar to Google Takeout exports). The main difference is that the MBOX format exports each folder as a separate file, while EML exports each email as a separate file. The Mbox format can be opened by Apple Mail and other mail clients, but unfortunately, Microsoft Outlook cannot open Mbox files directly on Windows. When you export emails, you have the option to download the files as EML or MBOX. The Proton Mail Import-Export app (new window) is available to customers with a paid Proton Mail plan and allows you to export emails from your Proton Mail account or import emails from your other email accounts or from files stored locally on your device.