Having an email address field with the email address visible to all site visitors is a potential spam risk to whomever has their details published in this way. We would not recommend that you add this as a field, however it is possible to do so using the custom form functionality already built into the theme. On a related note though, the contact business owner feature has been added to Vantage v1.2 (for which the beta version is due for release very soon), which will allow site visitors to contact a business owner through a contact form without the need for the actual email address to be published. Thanks.