Autoresponders

I don't know where on earth to post this question, but I am taking a shot in this forum. I am looking for an email program or some kind of program, preferably free. That can be set up for different groups to send autoresponses to customers. For example one group of people could be sent a reminder once every four days for 15 days or something like that. I would like it to email each person specifically instead of sending a bulk email to the whole list. Also I would like it to say Hi persons name, for each specific email. Is there such an animal???