Autoresponders are used by individuals and also by Web sites that need to respond to user comments automatically. For example, an individual may use an autoresponder feature of e-mail to inform the sender that he has gone on vacation and will not be replying personally to e-mails until he returns to the office; an enterprise may use an autoresponder in response to a newsletter subscription request to verify the opt-in or subscription cancellation or to indicate to the sender that a user comment was received. Autorepsonders are also used by enterprises to indicate that an online purchase was processed and will typically include an order confirmation number in the e-mail that is automatically generated and sent to the purchaser.