http://arstechnica.com/news.ars/post/20060211-6161.html
Google last night revealed their plans to offer Gmail service for third party mail servers. Currently in beta, the service will allow mail server operators to essentially hand the reigns over to Google's Gmail cluster. While details are currently limited (Google's own Terms of Service are not yet published at press time), I expect the technical implementation to be something such as this: Redirect your mail routing to Google (i.e., change your MX records) Customize Gmail so that it is branded for your organization, and e-mail appears to come from your organization. Either manually create new user accounts, automate account creation with a Google tool, or possibly use some kind of snap-in authentication.
