How can I set up Evolution to access a local mail box?

This answer follows the premise that you're using a mail spool, if its mbox format your mileage may vary:

• Start Evolution, then go to Tools -> Settings.
• Click Mail Accounts -> Add -> Forward.
• Type in a name in the Full Name field.
• For the Email Address field, type in your login ID followed by @localhost. For example: lazypower@localhost Click Forward.
• Click on the drop down list box and select Local delivery. If the Path field in the Configuration section isn't already filled in, you'll need to type in the location of your local mailbox. Using the login ID from above as an example, here's what would be entered: /var/spool/mail/lazypower Click Forward.
• If you like, you can setup Evolution to automatically check this mail account. Click Forward.
• You're not going to be sending mail with this account, so you could just leave everything alone in the Sending Email window. However, I change the Server Type to Sendmail. Click Forward.
• Finally, enter a name for the mail account. The name "Local Messages" is a good choice. Click Forward and Apply.

Thanks go to this post I've verified the instructions locally. Works without a hitch.