The other thing that would really be doing this client a favor is having a heart-to-heart about email housekeeping and cleanup, and on a continual basis.
Email should be treated exactly as real mail was: You touch it once, attend to what needs attending to now, keep a few things that need attending to a bit later, and delete anything else. What gets permanently filed, and there will be some, is only things you have reason to believe you might be called upon to look at again or produce much later.
That email you got from your spouse asking you to pick up the dry cleaning should never, ever, be in an archive.
Just because it's easier to search an email archive doesn't mean it's easy to plow through the results if you do not curate your archive as you go along.