While social media platforms like Twitter and Facebook are providing an alternative place for online interaction, email is still the gold standard for online communication. This essential piece of information is the bare minimum for sending out an eNewsletter and in that regard, should be the priority. The more fields that a person has to fill in to sign up for something online the less likely he or she is to end up finishing the sign up process. The prize that you're eye-ing is their email address. Everything after that is icing on the cake.

A good practice is to only require an email to sign up for the eNewsletter and when the user submits their email, they are taken to a second page with optional fields of information (name, address, etc.). That way, you already have the necessary piece of information for your mailing list (their email address) and only after they have provided it do you ask them for additional information. That way if they don't want to give you any more info than their email address, they can leave but you have already gotten their email. Those that don't mind filling out further fields of information about themselves can do so on the second page. Everybody wins. Those that don't want to be bothered with additional fields can ignore them and those that are willing to give you additional information are directed to where they can do so. And for both types of people, you have their emails.