E-mails, like all correspondence in the transaction of public business, are considered public records under the Virginia Freedom of Information Act. It does not matter if the e-mail was sent from a government server or a home computer.
The Virginia Supreme Court in 2004 ruled that e-mail correspondence in the transaction of public business is public record. The case is Beck v. Shelton.
The Freedom of Information Act does not provide guidance about how e-mail should be preserved.