Hello Jim,

You will want to start off by verifying what kind of digital form they want, A Pdf for each email, or would an archive file from Outlook or Thunderbird mail client suffice?

I would start by connecting Thunderbird to your yahoo mail account (IMAP) if you are prompted, it should auto-discover settings when your first enter your email address into the application.

After you let the Thunderbird mail client populate with your email, you can now export a copy of the Thunderbird mail profile to give to your lawyer, who will now be able to import it into an empty Thunderprofile for viewing.