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Large folder exported by ImportExportTools NG does not import correctly

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  • Last reply by jimboyle

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Failed ImportExport of a large folder.

Input folder of several hundred messages inThunderbird 78.8.1 was exported using ImportExportTools NG to a 600 KB file with filename "Inbox" and no file extension - which I understand is an mbox file.

Importing that file into a Local folder gives only one message.

QUESTION: How can all the messages in that file be recovered?

Failed ImportExport of a large folder. Input folder of several hundred messages inThunderbird 78.8.1 was exported using ImportExportTools NG to a 600 KB file with filename "Inbox" and no file extension - which I understand is an mbox file. Importing that file into a Local folder gives only one message. QUESTION: How can all the messages in that file be recovered?

Chosen solution

A large file containing several hundred messages would not be 600 KB in size, so the fact you can only see one message when it was imported is understandable.


What is the size of the original Inbox mbox file; check your 'profile name' folders. In Thunderbird

  • Help > Troubleshooting Information
  • click on 'Open Folder'
  • Exit Thunderbird now
  • If pop account click on 'Mail' folder
  • click on pop mail account name folder
  • If imap account click on 'ImapMail' folder
  • click on imap mail account name folder

Make sure you are using view details and the 'Size' column is visible. Locate the 'Inbox' no extension mbox file and check the size.

Q: What size do you see for the Inbox (no extension) mbox file? Q: Is this a pop or imap account Inbox?

At this point, if you have located the correct 'Inbox' mbox file and it has a good size, then you could copy and paste the 'Inbox' mbox file into the 'Local Folders' folder - located in the 'Mail' folder - same place as the pop accounts. Note: if there is also a 'Inbox.sbd' folder then it will contain Inbox subfolders that may also contain mbox files, so you can also copy that 'Inbox.sbd' folder into 'Local Folders' as well if desired.

then start Thunderbird.

See image as guide. It shows a pop account on left and Local Folders on the right, but it shows what an mbox file looks like which might be a helpful guide.


Normally, when using the ImportExportTools NG to export eg: Inbox:

  • Right click on Inbox folder in Folder Pane and select 'ImportExportTools NG' > 'Export Folder' or 'Export Folder with subfolders (with structure)'
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Chosen Solution

A large file containing several hundred messages would not be 600 KB in size, so the fact you can only see one message when it was imported is understandable.


What is the size of the original Inbox mbox file; check your 'profile name' folders. In Thunderbird

  • Help > Troubleshooting Information
  • click on 'Open Folder'
  • Exit Thunderbird now
  • If pop account click on 'Mail' folder
  • click on pop mail account name folder
  • If imap account click on 'ImapMail' folder
  • click on imap mail account name folder

Make sure you are using view details and the 'Size' column is visible. Locate the 'Inbox' no extension mbox file and check the size.

Q: What size do you see for the Inbox (no extension) mbox file? Q: Is this a pop or imap account Inbox?

At this point, if you have located the correct 'Inbox' mbox file and it has a good size, then you could copy and paste the 'Inbox' mbox file into the 'Local Folders' folder - located in the 'Mail' folder - same place as the pop accounts. Note: if there is also a 'Inbox.sbd' folder then it will contain Inbox subfolders that may also contain mbox files, so you can also copy that 'Inbox.sbd' folder into 'Local Folders' as well if desired.

then start Thunderbird.

See image as guide. It shows a pop account on left and Local Folders on the right, but it shows what an mbox file looks like which might be a helpful guide.


Normally, when using the ImportExportTools NG to export eg: Inbox:

  • Right click on Inbox folder in Folder Pane and select 'ImportExportTools NG' > 'Export Folder' or 'Export Folder with subfolders (with structure)'
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Thank you Toad Hall for your guidance that helped me solve the problem. As the mbox file was named "Inbox" I preferred to rename it as Old-Inbox before attempting again to recover the messages.

  • I closed Thunderbird
  • I copied the files Old-Inbox and the folder structure Old-Inbox.sbd as sub-folders of 'Local Folders' in the Thunderbird Profile folder.
  • I restarted Thunderbird
  • Voila! All messages recovered in their original structured mailboxes.

Now I can go back to messing with boats.