From 10.3 to 10.4 Lost or Hidden Messages

Question

I moved Mail from OS 10.3.8 to OS 10.4.6 and have everything in place and working well except my messages from INBOX and Sent Messages did not transfer.
In Home/Library/Mail/POP Acct - Inside both INBOX.mbox and Sent Messages.mbox I find a Messages folder but the only messages found in these folders are ones that were received or produced since installing the OS 10.4.6 (1 day old).
In OS 10.3 I had more than 4,000 small messages.
I have a cloned copy of my HD/OS 10.3.8 (connect via firewire mounted at the same time for comparison) and when I look in the same place in:
In Library/Mail/POP Acct. xxx/ INBOX.mbox/Messages folder
I can't see any messages but when I boot up to the 10.3 HD all the 4k+ messages appear in Mail.
As outlined in another posting I did as the incomparable Ernie Stamper suggested - I transfered both the com.apple.mail.plist from the Preference folder (Home/Library/Preferences) and the Mail folder?
Perhaps I should try trashing all of Mail in OS 10.4.6 and recopy all of Mail and Prefs from 10.3.8?
What else?
Any help on where my messages are hiding and how I can retrieve them would be very appreciated.
Gus
PowerMac G5   Mac OS X (10.4.6)  

Answer 1

I have to cox.net accounts in Mail. When I switched a few days ago from 10.3 to 10.4, only a few recent emails showed up in my inboxes in 10.4. All of my Sent messages were intact. And of the few emails that showed up in the in boxes, this message appeared in the body area:
"The message from Skye Knotts <[email protected]> concerning “New quarterly access code from Equifax” has not been downloaded from the server. You need to take this account online in order to download it."
So the message was lost even though the email itself remained. But hundreds of other emails did not transfer to 10.4. I don't know how to retrieve them.
I am receiving and sending emails just fine, however.