your remove the mbox file extension. When placing the files into local folder they must have no file extension.

Matt, thanks very much for your reply. I tried two things.

The structure is that I exported 3 of my Mail.app mailboxes to a folder named ALL_mailboxes that I defined in TB's Local Folders. Each of the exported mailboxes originally had this form:

 <mname>.mbox           folder
   table_of_contents    file
   mbox                 file

My first try was simply to rename the three *.mbox folders to remove the .mbox extension. This did not solve the problem. My second try was to throw away the table_of_contents files and move each of the mbox files up a level into ALL_mailboxes, each with the name of its original .mbox container. That didn't work either.

Maybe I'm mis-understanding what you described?

Not knowing what variant of mbox mac mail uses, perhaps using the import export tools might be a better way.

https://addons.mozilla.org/en-US/thunderbird/addon/importexporttools/

It's not sufficient to just remove the .mbox extension from the exported files created from 'Export Mailbox', as you found, but you may have better luck converting the elmx files to an mbox file that can be imported to TB, using e.g. this tool, or using 'File/Save As...' as explained here. The same article describes how to import to TB, either with the ImportExportTools add-on, or by manually copying the mbox files into the profile folder's Local Folders.

Matt said

Not knowing what variant of mbox mac mail uses, perhaps using the import export tools might be a better way. https://addons.mozilla.org/en-US/thunderbird/addon/importexporttools/

I have downloaded and tried the latest version of importexporttools. The doc says

if you want to import messages or MBOX files, you must first select a valid folder as a target, otherwise the import options are disabled

But I can't find anywhere to MAKE that selection. The Preferences allow entering a folder for exports, but not imports. But the selection for imports is disabled (gray). Can you tell me how to do that? (I have a feeling that the answer is something familiar to TB users, but I'm completely UNfamiliar with TB.)

Thanks.

sfhowes said

It's not sufficient to just remove the .mbox extension from the exported files created from 'Export Mailbox', as you found, but you may have better luck converting the elmx files to an mbox file that can be imported to TB,

Thanks for the suggestion. But I have over 100,000 emlx files, so I don't think that's practical.

or using 'File/Save As...' as explained here. The same article describes how to import to TB, either with the ImportExportTools add-on, or by manually copying the mbox files into the profile folder's Local Folders.

That article says it is obsolete, and the descriptions in it are from Mac OS X versions at least two older than El Capitan. Nevertheless I tried them, and they don't work. I appreciate your suggestions.

Note that mbox format is one file that contains multiple messages - all the messages in a folder. So, if you have 10k elmx files in a folder, they will be converted to a single mbox file.

Are you saying that there are no apps, including this one, that convert elmx to mbox, that work in El Capitan?

Thanks again for your response.

sfhowes said

Note that mbox format is one file that contains multiple messages - all the messages in a folder. So, if you have 10k elmx files in a folder, they will be converted to a single mbox file.

I do know that. But I currently have about 160 mailboxes containing over 100k (not 10k) emlx files. I certainly don't want to lose all of that organization by combining them willy nilly. And doing anything by hand 160 times is begging for human errors on a large scale.

Are you saying that there are no apps, including this one, that convert elmx to mbox, that work in El Capitan?

I think I'm making only two asserions. (1) I have no evidence that Apple didn't change THEIR definition of emlx files when converting to Version 3 of their Mail.app. The folder structure is truly unbelievably complicated. I've tried in the past to understand it, and failed every time. I have no reason to believe that the format of emlx files hasn't also become more complicated. (2) Even if the program runs under El Capitan, it may or may not produce a "correct" mbox implementation of the corresponding email for every emlx.

Since Mail.app has a reasonable "Export" function for Mailboxes that produces what look to me like perfect .mbox files for each Mailbox, all of the problems created by the complexity of Version 3 of Mail.app could be bypassed if I could just figure out what TB doesn't like about the mbox files produced by Mail.app. I suspect it's something very simple. It may just be that I'm not putting them in the right place, or with the right folder structure, none of which I can find any place. Might you be able to provide me with a bit more detail than I've found elsewhere, or maybe somewhere else to looK?

frazzlejazzy said

Matt said

Not knowing what variant of mbox mac mail uses, perhaps using the import export tools might be a better way. https://addons.mozilla.org/en-US/thunderbird/addon/importexporttools/

I have downloaded and tried the latest version of importexporttools. The doc says

if you want to import messages or MBOX files, you must first select a valid folder as a target, otherwise the import options are disabled

But I can't find anywhere to MAKE that selection. The Preferences allow entering a folder for exports, but not imports. But the selection for imports is disabled (gray). Can you tell me how to do that? (I have a feeling that the answer is something familiar to TB users, but I'm completely UNfamiliar with TB.)

Thanks.

I have never used OSX, but based on the question those using it ask it must be a dreadfully boring operating system with limited options.

Right click (command click) a folder you have created in the local folders structure in the folder pane. Select importexporttools from the pop up menu. Proceed with your import.

Not being a Mac user, I really can't offer much advice that you can't search for yourself. But I suggest you try the process of converting a sample of elmx files to an mbox file and seeing if the import to TB retains the original Mail app messages. If it doesn't work, you haven't wasted much time; otherwise, it offers a means of migrating the rest, in the absence of knowledge about the incompatibility of Apple's mbox format with TB's.

I am slow, but I just spent some time on Google and it appears apple MBOX files are something apple calls a package and in no way resemble a real mbox file. So I must thank the nice folk at Cupertino for yet another confusing approach to something simple. A truly Apple approach really.

SO from my reading, if you save one of these mbox files to the desktop and double click it you get OSX showing you a folder inside with the actual mail in it called mbox which is the actual mbox mail you want.

See https://bugzilla.mozilla.org/show_bug.cgi?id=688166#c23

Matt said

Right click (command click) a folder you have created in the local folders structure in the folder pane. Select importexporttools from the pop up menu. Proceed with your import.

This is the key piece of information I was missing. Getting it did not solve the problem, but it allowed me to figure out how to solve it. THANKS! (I have marked it as "solved" by this answer.)

Matt said

I am slow, but I just spent some time on Google and it appears apple MBOX files are something apple calls a package and in no way resemble a real mbox file.

Just to clarify things, that's not right. A "package" is a wholly different animal that has nothing to do with email. An Apple "mailbox" is a folder (not a file), but its structure has changed with each new Version of Mac OS X's Mail.app . El Capitan is up to Version 3, and the structure of the stuff in that folder for a "mailbox" is what is so incredibly complicated.

SO from my reading, if you save one of these mbox files to the desktop and double click it you get OSX showing you a folder inside with the actual mail in it called mbox which is the actual mbox mail you want.

You can get such folders by invoking the "Export Mailbox..." function after selecting one or more Mailboxes. That's what I'm doing. The resultant folder(s) each contains 3-4 files, one of which is the actual mbox I want. I can write a simple program to manipulate these folders to produce what I now understand that TB wants to see.

See https://bugzilla.mozilla.org/show_bug.cgi?id=688166#c23

The last line in that reference is talking about the same technique I'm using. But it doesn't maintain any tree-like structure within the set of Mailboxes. (Apple Mail allows a mailbox to contain a sub-tree of other Mailboxes.) And, as mentioned, it's impractical if you have a LOT of Mailboxes.