The Fox DataDiode software allows email to be sent to a secure network. Email can be sent from a user or application in one network to a user or application in the other network. This is useful for users working in one or both networks wishing to share information or data files as attachments to emails.
Users working with two networks can, for example, forward their public email to their account on the secure network. This way, they do not have to switch workstations to check for new e-mail.
The way e-mail forwarding with the Fox DataDiode works, is explained here.