There is one of the reasons why I didn't want to be a lawyer...
First, since your attorney probably has a computer himself, I'd give him the mails in "electronic" format = as files... nothing unusual these days, and he's getting paid for making evidence work as such, right?
You can even email the mails to him:
- Assuming the mails have something in common, create a new "Smart Mailbox" to have them all in there. Alternatively, you'll need to create a regular new mailbox and copy them in there manually.
- With that mailbox open, select them all (e.g. by selecting one, then pressing Command-A), then under "Message" in the menu bar click on "Forward as Attachment" (or right-click on the selected mails and choose the same command).
The rest should be self-explanatory.
Just an additional thought in case you do decide to email them:
If they contain any sensitive information, I would not send them unencrypted. I had to forward quite a few some time ago; I copy/pasted them into Pages chronologically, condensed them where I could, exported it as a .pdf and then encrypted the file. Sent two emails: the first contained the password necessary to open the file, and the second simply had the pdf attached.