I've moved mail from machine to machine (10.2.x to 10.3.x, and 10.3.x to 10.3.x), but I have heard some grumblings about upgrading to Mail 2.0 (used in 10.4) I have yet to really poke around 10.4, so I can't be 100% as to the problems and the proccesses, but a way to I've used to get mail from one 10.3 computer to another is to boot your older eMac in fire wire mode (hold T on startup). Connect your old eMac to the newer one (you could use Cat 5, but firewire is quicker, depending on the amount of mail you want to transfer). Take the folder called Mail (Users/[name]/Library) and place it into the corresponding location on the newer machine. Start mail on the newer machine and your account should transfer. You may have to fenegle it a bit (it's been awhile since I've done this but I know it's possible at least from 10.3's POV) but it should work. Of course, all this hinges on the fact that Mail 2.0 keeps it's mail in the same location, and that it will be able to read the Mail 1.0 files... If it doesn't work, you can always downgrade your newer eMac to 10.3.x, do the transfer, then upgrade it to 10.4... seems a bit cumbersome, but since no one else has replied, I figured I throw in my .02...
