If all these emails are either sent or copied to a single place, just about any email software would do the job, including the free Windows Live Mail. It runs with XP, Vista, Windows 7 & 8. If not, then you'd have to export them from the various sources, then import them at the central place. If you have MS office, you could also use Outlook.
I am the director of a corporation which builds homes utilizing tax credits. 95% of the business conducted between all parties was through email and attachments. I am looking for a program or software that can take the hundreds of emails and attachments and put them into a chronological report, so people can see what the process was. Any clues?