I worked on a person's computer recently and he made the observation
that three months worth of his e-mails were missing (and NOT deleted
by this person - the emails = $$$ to him). Anyone have any
explanation on how this could happen?

Obviously my recommendation needs to be to ditch OE to this person (I
noticed it doesn't handle anything past about 300 messages well), but
what can I tell them to explain this happening?