I cannot afford to lose either emails OR the folder structures. I don't know exactly how many folders I have, but it's thousands. These are customer correspondences, I retain for reference and often need to research past messages for various reasons. I can't just have everything in one place, I'd never find it.
Again, appreciate your time in corresponding, but I just don't think that will work. I'd have to upload probably 20,000 (maybe more emails), then re-download into new client and then re-create the 1000's of folders to put the emails in. Not many people have that kind of time... I know I certainly do not.