How to read email within a PST compacted by Thunderbird?

Question

After running out of space on gmail, I downloaded all emails to the desktop using POP3 with Thunderbird as the client application. Whilst downloading the emails, on two occasions Thunderbird asked to compact the PST file. This option was accepted.

After all emails were downloaded, some of the mails loaded during the period for which mails were compacted are no longer fully available. By this I mean a general search (sender address, subject etc) from Thunderbird displays the email sought. Yet when I drill down into any particular email, the email is not displayed.

Using Thunderbird, how do I read any particular email that is part of a compacted PST?

Answer 1

Regarding the comments, I think, here is a general confusion about the acronym "PST":

PST is "reserved" by Outlook as its internal local mail storage format.
Thunderbird doesn't handle this format and will not create it.

=> So I'm sure you've not seen "PST" in Thunderbird but talk about something like "mail folder".

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Depending on the configuration, Thunderbird should have created files in the "mbox"-format while the mail download via POP3. Additional to the mbox formatted mail file an index-file (*.msf) is created aside. In the simplest form you have the files:

INBOX       # visible as the INBOX folder
INBOX.msf   # the associated index file

If Thunderbird asks to "compact" a mail folder (not PST), then this is similar to a database action to compact:
When deleting mails, these mails are only "marked as deleted". By "compacting" these marked mails will be physically removed (the mbox file will be rewritten without the deleted files and the index file gets recreated).

=> So there is no way to find your missing mails in a "compacted" mail folder if they are not visible anymore in the "normal" view. They are not present anymore in this mbox file.

You can test their presence by searching some keywords in the file "INBOX" at the command-line. The file you'll find here:

# Linux:
~/.thunderbird/<cryptic-id>.default/Mail/<mailaccount>/INBOX

# Windows:
C:\Users\<User>\AppData\Roaming\Thunderbird\Profiles\<cryptic-id>.default-release-1\Mail\<mailaccount>\INBOX

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Probably you will say: "I didn't delete any mails."

This might be true and is plausible: Thunderbird in its default settings will archive mails of a distinctive age. — As you moved a huge mail history from Google to the local Thunderbird, there surly will be several matured mails that probably immediately got archived.

This achieving process means:

1. Copy the mail to the "Archive" (another file in mbox format)
2. Delete the mail from the "INBOX" (mark as deleted)
3. As the trigger value has been reached after several of these moves, Thundebird asks for "Compact the mail folders?" and removes the "marked as deleted" mails frome the INBOX file.

=> I would expect that you will find your missing mails in Thunderbird's "Archive" folder, located nearby the "INBOX" and the other default folders like "Trash" and "Sent".

If this scenario turns out to be your solution and you don't like it, then I would suggest you

1. switch off the "Archive" feature in "Account Settings » Copies & Foders".
2. Then you can sort your archived mails to the place you want them to be.