MailSteward will archive all of your email in a database for easy retrieval, without touching or modifying the email in your email client program. Just click on the Store Email in Database button and MailSteward will go to work storing copies of all your email, both text and HTML versions, and attachments, into a relational database file. You can then retrieve email and attachments from the database by searching on Date, From, To, Subject, Mailbox, or Body text.
Standards-compliant Java persistence via JDO/JPA/REST and RDBMS/db4o/Excel/LDAP.