>Cans Thunderbird store all attachments in a designated folder? If so how is this done?

Nope, Thunderbird keeps the messages as they were, with full headers and all attachments in MIME paragraphs (which is plain old base64 - see strconv() to convert those).

When exporting them you can just "Save all" and then manually pick a folder where they will be saved. To do anything programmatically, you may open the inbox as a text file, using fOpen() (filetostr() may choke you, it's one huge file, I got a few which are over the 2G mark), but then finding the message in that huge string would be a task unto itself. I did that once, and the code still works, but it chokes above certain sizes, because I store the lines read into arrays (which I then analyze to find headers and store their offsets and message lengths into a dbf). Kind of messy, but it works. And if need be, I can then cut out the message, save it into a temp file, and extract the attachments into any folder I want.