When entering a new constituent we always try to have at least an address or an email, but if the information comes to us through a referral or a newsletter sign up list we do not always get both. As of this time, we don't have either field marked as required, since we don't always get both.

In practice that means constituents records can be created without the system prompting to enter either an address or an email. What I would like to see is if neither parameter is included, having a prompt to add one or the other. But once either type is added being able to go on and save that new constituent.