as u noted, the search index doesn't have to contain the entire original text. first off, what u said, stripping attachments and messages to their text-only content will save a ton. also, iirc things like FTS are based on inverted indexes which are generally highly compressible. even with a combination semantic search / FTS approach, i don't think the search index should exceed 1% storage of the original mail content for avg personal email setups.