Keeping Personal Electronic Mail (Library of Congress)
http://www.digitalpreservation.gov/personalarchiving/documents/PA_email.pdf
Guidelines for keeping your email preserved over the long term.
Archiving Email (Library of Congress Personal Digital Archiving Series)
http://www.digitalpreservation.gov/personalarchiving/documents/archive_email.pdf
More specific than the previous document, this 2-page brochure will further acquaint you with ideas and terminology important in email archiving.
REPORT
Prom, C. J. (2011). Preserving e-mail (DPC Technology Watch Series No. DPC Technology Watch Report 11-01). Salisbury, UK: Charles Beagrie Ltd. Retrieved from http://dx.doi.org/10.7207/twr11-01.
TOOLS
THUNDERBIRD: Thunderbird eMail Archive (Mozilla)
Thunderbird is a free, open source email system developed by Mozilla. It works across multiple platforms and includes options that allow for sophisticated archiving abilities. While the email server portion is fairly easy to use, the archiving features may require an intermediate level of computer skills.
EMAIL VISUALIZATION: MUSE (Memories Using Email) software
http://mobisocial.stanford.edu/muse/
Although not for preservation, this research project from the Mobisocial lab at Stanford University presents a downloadable software package will help you make sense of the contents of your email archive. At present, the software is optimally used with archives of 50,000 messages (http://mobisocial.stanford.edu/muse/tipsheet.html).
Related article: Hangal, S., Lam, M. S., & Heer, J. (2011). MUSE: Reviving Memories Using Email Archives. In In Proceedings of the 24th Annual ACM Symposium on User Interface Software and Technology (UIST ’11) (New York, NY: ACM, 2011), pp. 75-84. http://dx.doi.org/10.1145/2047196.2047206. Retrieved from http://xenon.stanford.edu/~hangal/muse.pdf