How [not] to upgrade to Mail in 10.4
Update:
Thank you, Andy Warwick! I'm leaving the following article online, just so I remind myself how much time I wasted on this. However, the comment from Andy (#9 in the chain) pointed me to what I was doing wrong. So for anyone who hasn't imported their email yet, the trick to using the Mail for OS X import function is this: simply point it to your old user's Library/Mail folder, no deeper.
I still think Apple's language could have been clearer (see my #10 comment), but I retract the other nasty things I said about the import routine. When pointed at the correct folder (I just tested it), it worked like a charm. Good job, Mail team. Now how about making the import screen read simply "Please navigate to the previous Mail folder"?
This is a follow-up to my The Art and Science of OS X System Upgrades article. I'm (still) in the process of upgrading my main drive, having just finished migrating my email archives last night. Why did it take so long? User stupidity plus, in my opinion, some poor functionality in 10.4's Mail import routines.
As noted in the earlier article, I had chosen to do an upgrade install on my main drive, but to not automatically copy over my user's folder (due to all the cruft in it). It was this decision that ended up costing me many hours of email migration labor. Why, you might ask, did it take so long?
After I got 10.4 up and running, before doing much of anything else, I launched Mail and set up my two primary accounts, just so I could keep up with email while doing the rest of my work. Mail may have asked me about importing old email when I first launched it, but I don't think it did -- my ~/Library/Mail folder was empty, since I hadn't moved the old Mail folders over. Apparently if you allow the user information to migrate, Mail will automatically import your old Mail messages. Ah, I should be so lucky...