An Auto-Responder Email is an email that is automatically sent to an Internet Lead immediately after they submit a form. It could take the form of a welcome message to a new subscriber for an email newsletter, or a thank you message to someone requesting information about a product or service. Auto-responder emails are a very important tool for converting prospects into customers. They also serve as a method for determining the validity of the email address used on the form. For email newsletters it is good practice to have the user double opt-in by clicking on a link in the welcome email. Sending auto-responder emails is typically accomplished through the use of an Email Service Provider.