Good question...let me try to answer it for you. What you are referring to is an 'Autoresponer' service.For all my email marketing campaigns, I use an excellent Autoresponder service provided by a company called Aweber. Just google their name and click the link to their site. On there you will see exactly what you are looking for and more..they really are worth their weight in gold.
At the moment, they are offering 30 days free too. There are completely free sevices out there (free autobot.com) but they don't offer as many options.
If you goto youtube and type in aweber in the search box, you will find lots there too.
To finish, if you are REALLY serious about capturing leads and learning how to maximise your revenue from email campaigns, then there is no better course on the market than the one I have been using. My list exploded literally overnight and with quality, spending leads too. See the source below.
I hope this is helpful to you,
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james-allenreview