When a user shifts from one email application to other he/ she needs to export the data too.

As the email applications use different file format to store data, so to make it compatible with other mail application one need to convert the file format too. Taking the example of Thunderbird to Outlook, we need to export the MBOX files to PST. There are lots of commercial MBOX to PST converters available to transfer files, however, the user should be ready with manual method too as, by these, one can convert files instantly for free. 

Keep in  mind, converting MBOX files to PST is not a direct process. The MBOX files are first converted to EML format and then the EML files are exported as PST to use by Outlook.


Thus for MBOX to PST conversion, one has to 

  • Connect a common email account with Outlook and Thunderbird
  • Now convert the MBOX files to EML
  • Move EML files to Outlook
  • Convert EML in PST.


In detail follow the given steps for MBOX to PST conversion

Create and Add Account in Thunderbird and Outlook

  • Create a Gmail account
  • Open the Gmail account and then go to settings
  • Click on 'POP/ IMAP forwarding' and then click on IMAP enabled
  • Add the Gmail Account in Thunderbird and Outlook both using Account settings

Move mails from one mailbox to another

  • Open Thunderbird and then go to the section where Gmail account is added
  • Right click on the folder pane and select New folder
  • Give the folder a name and select the Gmail account under 'create as a subfolder of' option 
  • Finally, click on create folder button.
  • Now in Thunderbird mailbox select the messages and items you want to export
  • Right-click and send the emails to the new folder with path Move to>>Gmail Address>>Inbox>>Name of New Folder.
  • Open the Messages in the new folder and right click
  • Select save as and save them in EML format.
  • Now Open MS Outlook
  • Refresh the Inbox for new messages and changes
  • You will see the new folder created in Thunderbird in Outlook too as both are connected via Gmail
  • Open the messages in the new folder to confirm.

Export to PST

  • Open Outlook and launch the Import/ Export Wizard
  • Select the option 'Export to a file' and then Outlook data file (.pst)
  • A new window will open to select EML files, here select the new folder in which EML files are stored and then checkmark Include Subfolders
  • Browse path to save PST file
  • Select 'Do not export duplicate items' and then Finish
  • The files will be converted in PST format and save in a new folder


So, this is the easiest and free method to convert MBOX files in Outlook PST format manually. This method is applicable to all MBOX based applications such as Thunderbird, Spicebird, Apple Mail, Netscape, Opera Mail, Eudora and many others.