That's an interesting question.

Your messages are stored back-to-back in a file. So when we re-sort the display, it doesn't re-sort the message store. Re-writing a large file would be slow and inefficient. So the re-sorting is performed at the indexing level.

I suspect, and this is only a guess on my part, that the export tools pick out the selected messages and read them out of the message store in the order in which they are encountered, no respect being paid to the display sort order. That's a shame, since it would not be impossible (IMHO) to honour the display sort order.

Why do you want to export them? People do this and I wonder why. Email messages in a conversation have a natural flow and logical relationships to one another, and pretty much all of this is lost once they are extracted from the email client. It seems to me that disparate independent text files are harder to manage and work with than email messages stored in an email client.

I'd look at exporting the messages to a CSV file, where it is possible that time and date data might be exported into its own columns, against which you could then sort.

The folder I am trying to sort is a merger of two different mail folders. Sorting by the date would put the conversation back into its proper order within a single file. Once I have that, I have other plans for the resulting sorted text.

Saving to a .csv file won't work. The dates and times will end up in different columns.

A keyboard macro might end up being my best solution, combining the down arrow and <CTRL><Shift>M sequences to step through each message and save it to a new folder. Unfortunately, if the macro tool doesn't support a repetition count, I'd have to invoke that macro about 3000 times. Any recommendations on this?

But in a spreadsheet file you could construct a composite date + time column and sort on that. I have had to do that many times when collating material, usually measurement logging, from disparate sources. You say "will" - is that hypothetical, or have you actually tried it?

Thunderbird doesn't have a keyboard macro tool. If you have an external keystroke record/replay tool then by all means try it.

Exporting to a csv file, using the ImportExportTools add-on looks good to me. It helps that I choose to format date and time as yyyymmdd hh:mm so these text fields when exported to a spreadsheet are inherently sortable. (That's why I use this format.)

The weakness is that you don't get to choose which time/date is exported. It exports the timestamp from the message itself, which I believe happens to be what you wished for.

If your date and time are in some other format then you may have to dissect their elements in your spreadsheet in order to generate a date/time serial number, then sort on that column.

I have never used the ImportExportTools add-on. I'll give that a look.

The folders originated on two different systems and predate Thunderbird in both cases. While this did not pose problems as far as getting Thunderbird to read the integrated file, a simple text save with edits crafted to break entries apart on "<CR>From " produces an unevenly aligned .csv file as far as the dates go.

If anyone has recommendations on an external macro tool, I'd welcome the input.

Followup: ImportExportTools appears to have saved the file exactly how I want it saved. I was able to save it directly in sorted order as a text file. Thanks!

Also of note: when writing the contents of a folder to a single text file, ImportExportTools preserves the sort order currently being displayed -- regardless of that order type.

The one drawback is that the "From " lines (vs. the "From: " lines) are removed from the resulting text. However, this is something one could easily fix with a Notepad++ macro if necessary.

For those who want to create a Thunderbird-readable file sorted by the message date, my ultimate solution was to modify the options for ImportExportTools to save .eml files with filenames using the date and time, then subject, then index. After that, I was able to export the messages to a folder in EML format, make a new folder, and re-import the files into that folder.

Other filename options beyond those given above are to identify each file by sender, recipient, or the combined sender/recipient names.

Thank again to Zenos for the lead on the ImportExportTools add-on!