Postini services include spam & virus protection, inbound/outbound content filtering, and policy enforced TLS as well as message archiving. These can each be bundled with Google Apps or can be used with third party email servers.
Google Message Discovery
Google Message Discovery is e-mail archiving and e-Discovery. E-mail archiving is now considered a non-negotiable core component of messaging infrastructure. Email archiving captures and indexes all of your organization’s sent and received email and attachments in one centralized, searchable cloud based repository.
