The present invention discloses a pre-processing summarization technique that makes use of knowledge specific to the electronic mail domain to pre-process an electronic mail message so that commercially-available document summarization software can subsequently generate a more useful summary from the message. The summarization technique removes extraneous headers, quoted text, forward information, and electronic signatures, leaving more useful text to be summarized. If an enclosing electronic mail thread exists, the summarization technique uses the electronic mail message's ancestors to provide additional context for summarizing the electronic mail message. The disclosed system can be used with IBM Lotus Notes and Domino infrastructure, along with existing single-document summarizer software, to generate a summary of the discourse activity in an electronic mail thread dynamically. The summary may be further augmented to list any names, dates, and names of companies that are present in the electronic mail message being summarized.