relational database for personal email storage

[R. Luoma]

I was wondering if anyone has stored locally their email
in a local relational database.  I am not planning
to use it as a email server, so the webmail solutions
that I am running across on my net searches seem like overkill.
I would also like to be create my custom SQL queries;
my email directory tree is getting a bit slow
to find-and-grep and there are some queries that I want
to make that do not easily fit the find-and-grep method.

What suggestions do people have?

-- 
R. Luoma