From the CALO Project at Carnegie-Mellon University a massive dataset of emails recovered from discovery documents in the Enron trials
From distribution page:
> This dataset was collected and prepared by the CALO Project (A Cognitive Assistant that …
ICPSR offers more than 500,000 digital files containing social science research data. Disciplines represented include political science, sociology, demography, economics, history, gerontology, criminal justice, public health, foreign policy, terrorism, health and medical care, early education, edu …