Once Leopard was installed I began moving over necessary files, including my Mail files.

To get your new version of Mail to recognize your old mail (so you don’t have to recreate all of your accounts), you need to move over the following files and directories:

• ~/Library/Mail/

• ~/Library/Mail Downloads/

• ~/Library/Preferences/com.apple.mail.plist

I did this and about an hour later realized that when I searched for previous emails I was only getting results from the past 10 days or so and emails that were still sitting in my Inbox before the install were now missing.

So…how did I fix this? It’s actually really simple.

After moving your Mail files over, you basically need to force Mail to re-index your mail files. To do this, simply select each mailbox and folder, one at a time, and go to Mailbox > Rebuild in the menu. Depending on the number of emails in those accounts/folders, it could take up to a minute or two to rebuild it. After that all of your previous emails should be accounted for!

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