I'm looking for suggestions about how to create an "email archive"
-- an electronic file cabinet of correspondence -- that is independent of any of the several email reader programs
-- evolution, thunderbird, outlook etc -- and independent of the workstation platform -- WinXX, Linux, Solaris, Mac OS, etc.

If the community call these things something other than "email archive" please tell me so that I might STFW using more effective language.

If there are good tools that are specific to given email readers
start by point me to those.

Each of the applications will keep messages in folders according to some plan. Each application implements this keeping folder differently on WinXX than on *nix. Sometimes each message is its own file. Sometimes each thread is a file. Sometimes each folder is a file, sometimes a folder is a folder with threads doing folder trees.
Sometimes the_full_message_subject_is_the_file_name
Other times the names are some numbers with a separate file as the index. Yada Yada...

{wishlist}
I'd like to read any utility specific email files and folders
and get (1) plain text files, and (2) PDF files into some sort
of folder tree. Text-only messages would become plain text.
Rich text (HTML &c) would become PDF. Something reasonable would happen with threading. Something reasonable would happen with attached documents or images or web pages or video.
{/wishlist}

I currently use Thunderbird because it is available for all of the platforms where I work. I must use Outlook on some WinXX workstations. I really like Evolution on Linux, but the Win32 implementation is not really ready, and it is not available outside or WinXX+Linux. My Linux of choice is Ubuntu.

Thanks in advance,
~~~ 0;-Dan

I think you're confusing two aspects of mail here.

There is the client aspect where things like viewing rich text, viewing plain text, viewing messages take place. Then there is the server aspect where the files are stored in either mbox or Maildir format.

I don't know of any product that does what you're looking for.

You could achieve a similar result using almost any imap client and the messages stored in Maildir format on the server provided the client is configured correctly and you've got procmail or something similar duping the messages off to a separate archive if required.