A Autorespondedor is a vital tool to carry out activities of Marketing by Internet as it is it to have a dominion or hosting professional. A Autorespondedor is a software that allows to send or to respond of automatic form messages to a list of subscribers who previously have let their at intervals regular data to receive time information. Following the service of autorespondedores that is contracted, this it will allow to handle lists of subscribers who go from hundreds to thousands, reason why is advisable to contract this service with a company that allows to handle great lists, since like any type of business, it hopes that this every day in potential clients grows more. Additionally, as they handle many e-mails, this service must allow to take a consolidated inventory and updated of the people to which information is sent to them, whatever of them read the information, whatever make request of not receiving more information and whatever are asking for the information shipment. Also this service must allow to add, to eliminate or to block accounts of e-mails. When some type of activity of Marketing by Internet is had, first it is to obtain a person interested in which this offering itself, to which we will call contact, this it makes its request receive information related to the product or offered service; at this moment the autorespondedor begins to work, since from this it is begun to regularly send messages to him to this contact giving information and motivating it to the purchase, to this series of sent messages denominates campaign to him. As one is all this operation of shipment of e-mails is totally automatic and the unique thing that there is to create is the campaign which enters operation without concerning the number of contacts that is had. However the service of autorespondedor that is in Internet has several characteristics; these can be contracted per month, semester, annual or life; others need to be installed directly in hosting there are and them also limit or the amount of campaigns that can be created or amount of contacts that can be had. Thus then if it is required to harness the activities of Marketing by Internet, to have autorespondedor it is essential and are many the companies that offer this service, but at the time of making the hiring general aspects are due to consider such as: Language, ease of use, installation, technical support, maximum amount of campaigns and contacts, price, speed and trustworthiness.