US Patent 7836099 Mail compression scheme with individual message decompressability

Embodiments of the present inversion relate to a two-pass compression scheme that achieves compression performance on par with existing methods while admitting individual message decompression. These methods provide both storage savings and lower end-user latency. They preserve the advantages of standard text compression in exploiting short-range similarities in data, while introducing a second step to take advantage of long-range similarities often present in certain types of structured data, e.g. email archival files.