Thunderbird Folder Repair

Thunderbird_Glass_Wave_1600x1200A repair can often help if you are experiencing issues with Mozilla Thunderbird such as missing messages. We will discuss a few steps for Thunderbird folder repair.

Thunderbird Folder Repair Steps

Unwanted Inbox Zero?

Is your Mozilla Thunderbird inbox suddenly much lighter, but you haven’t deleted any messages? Or did you delete a message weeks ago, and it is still showing up in your folder?

The appearance of Mozilla Thunderbird folders sometimes loses track of the underlying structure: messages actually present are not showing, or deleted emails are still present. Fortunately, Mozilla Thunderbird can re-build the folder index. This allows the message list to show faster than if the folder’s full contents had to be loaded. Therefore, it will reflect what messages you do have.

Repair Folders in Mozilla Thunderbird

To rebuild a Mozilla Thunderbird folder — when emails have disappeared, for example, or deleted messages still show, perform the following steps:

  1. Turn off automatic mail checking as a precaution.
    • Typically, this is not necessary but it avoids a potential cause for conflicts.
  2. Next, click on the folder you want to repair in Mozilla Thunderbird with the right mouse.
  3. Select Properties from the menu that appears.
  4. Go to the General Information tab.
  5. Click the Repair Folder and then click OK.
    • You don’t have to wait for the rebuilding to finish before clicking OK. However, make sure to to wait before doing anything else in Mozilla Thunderbird.

Have Mozilla Thunderbird Rebuild Multiple Folders

If you want Mozilla Thunderbird to repair more folders’ indices automatically, perform the following:

  • Make sure Mozilla Thunderbird is not running.
  • Open your Mozilla Thunderbird profile directory.
  • Click on the desired account’s data folder.
    • IMAP accounts are under ImapMail.
    • POP accounts are under Mail/Local Folders.
  • Locate .msf files corresponding to the folders you want to have rebuilt.
  • Move the .msf files to the trash.
    • Be sure not to delete the corresponding files without extension.
    • If you see a file called “INBOX” and a file called “INBOX.msf”, for example, delete the “INBOX.msf” file but leave the “INBOX” file in place.
  • Start Mozilla Thunderbird.
  • The removed msf. (index) files should be rebuilt automatically by Mozilla Thunderbird.

Copying the Message

Using the following steps to copy messages in Mozilla Thunderbird between accounts:

  1. Select the message(s) that you wish to copy to the same folder to another account.
  2. Click one of the selected message(s) with the right mouse.
  3. Select the Copy To option.
  4. Next, select the Email account you want to copy to.
  5. Then, select to further drill down to the folder you wish to copy the messages to.
  6. The messages will start to copy once at the lowest level of selection.
  7. The original messages will still remain on the original server.

Moving the Message

Move messages between accounts in Mozilla Thunderbird using the following steps:

  1. Select the message(s) that you wish to move to the same folder in another account.
  2. Click on one of the selected message(s) with the right mouse.
  3. Select the Move To option.
  4. Next, select the Email account you want to move to.
  5. Then, select further to drill down the folder you wish to move the messages to.
  6. The selection of messages will start to move once at the lowest level of selection.
  7. The original messages will be removed from the original folder.

Looking at the Messages in the New Account

To look at the messages in the new account, select the folder of the account you have just copied the Email messages to. Then, find one of the Emails that contains an attachment. When you attempt to view the attachment, you will receive the message described at the beginning of this document:

This attachment appears to be empty.
Please check with the person who sent this.
Often company firewalls or antivirus programs will destroy attachments.

Rectifying the Error

Perform the following steps to resolve this Thunderbird folder repair issue:

  1. Click on the folder with the right mouse.
  2. Select Properties.
  3. Click the Repair Folder option.
  4. Now select a different message and then the one with the attachment.
  5. Select the attachment and it will now open.

Perform these steps with any folder where you receive this error with attachments and you will be able to view them again. Most of the issues revolve around the incorrect setting of MIME boundary and the repair folder sorts these out so that the attachment can be found again.


If you have any questions about Mozilla Thunderbird folder repair, contact us here at Centennial Arts with the link below!

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