Yes, we offer online banking and, yes, we post our email address all over our site, including the primary internet banking page. After thinking about it, a guess we do promote the use of email, simply by posting our email address. The important issue is the posting of the email disclaimer (security/privacy issue). The disclaimer should be a pop up page that is linked from an "EMAIL SECURIY" button on various pages throughout your site.
With that said, the use of email by customers is a dangerous activity due to the fact that you cannot control what they note within email messages, so you had better clearly post a security disclaimer.