Companies may be required by contracts, or by discovery demands in litigation, or by lawful demands from law enforcement authorities, to search and turn over company records, including email sent or received by company employees.
Companies need to be careful not to make promises to their employees that are inconsistent with the company's obligations to other parties. And employees should be warned that the electronic messages they send and store may one day be required to be disclosed to other parties.
Note also that the need to preserve records for litigation may give rise to orders prohibiting the destruction of any records. This can create serious problems for regular archival and backup procedures.