The WikiLeaks website allows you to view individual emails, but I couldn't find a way to download all of them at once. This script does the job- slowly, but it functions. It returns a .csv with columns for Date, Subject, From, To, and Message Body.
I've succesfully run it for only 500 of the ~20,000 emails, and am currently attempting to get all of them. If it works I'll upload the resulting file here.