Thunderbird MSF File Viewer

Know the Unknowns of Thunderbird MSF Files

  • What is an MSF File Extension?
  • How to view & read Thunderbird MSF File?
  • Where does Thunderbird Stores Emails?
  • How to View Actual Thunderbird Emails?

Thunderbird MSF File Viewer

Where is my Thunderbird Emails?

I installed the latest Thunderbird 38.4.0 on my new computer. Old Thunderbird MSF files were then moved from the Thunderbird folder and placed into the new Thunderbird 38.4.0 store folder. I have configured my account using IMAP.

Problem with Thunderbird Emails

  • When I am trying to read my Emails I am unable to see anything & it is showing empty folder only. How can I view my Emails from MSF files?


  • To solve the challenge first we should learn about the MSF file and what data it holds.

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Software to view Thunderbird Mbox emails

What is MSF File in Thunderbird and What Does It Hold?

The Thunderbird stores user data (Email) in two parts. The first one is an MBOX file (without extension), which is a standard format of Mozilla Thunderbird client to store Email content. The second is an MSF file, which is also known as a Mail Summary file with .msf file extension. This is the index file of Mozilla Thunderbird, which contains only headers and summary of Emails. Thunderbird view MSF File (only index) to locate the emails stored in .mbox

Other sub-containers like Draft, Sent, Trash, and may be stored within .sbd directory. In this folder, you can find the pair of each container like Trash.msf & Trash, Draft.msf & Draft etc.

How to View MSF File?

As per the above description inorder to read MSF File we must know about MSF file. MSF is an index file, which does not hold the text content of Email message. Therefore, in the above scenario the user only placed the header and summary of emails and not the whole data (mbox file). Instead of reading Thunderbird MSF files, you need to check for MBOX file in your Thunderbird, which is without an extension. To verify if the file is of MBOX type or not, follow the tips:

  • Check the File Extension: The file like "INBOX, OUTBOX, etc." will be displayed without any file extension.
  • Check the file size: The MSF file are sized only a few KBs whereas the MBOX email file of Thunderbird will be of a larger size (If your Mailbox contain emails)

Where are My Emails Stored in Mozilla Thunderbird

In Thunderbird 38.4.0, the location of a MBOX file is:


Here you will find the INBOX file, which is the MBOX file of configured account. Now, you need to copy this Inbox file and place it to a different location on your PC, then Rename it as Inbox.mbox. Since .msf does not hold any email you cannot view msf file, but you can read emails through below methods.

Steps to View Actual Thunderbird Emails

First Download & Launch Thunderbird Import Wizard

Install Tool

Choose from two different Options "Add File or Add Folder" option.

  • Add Files To add Multiple files selectively
  • Add Folder To add bulk MBOX Files at Once.

Add files

Now you can Preview the added file within the interface of the software to see MBOX file

View Added file

You can Apply Date Filters to which can filter out data according to date feature

Date Filter

Then, Select Identities from the drop-down menu showing all the email-id configured in Thunderbird.It will automatically fetch the configured-id & display.Then Click on ""

Select Identity

Now You can View the MBOX File in Thunderbird Email Client

View Emails In Thunderbird

Recommended Tip:

The next time if you want to open Thunderbird MBOX files in other Email clients like Outlook, you can access your entire emails in Outlook by trying Thunderbird to Outlook converter Software, which saves much of your time as it automatically finds the MBOX file from the configured profile.