It's not a good idea to go the free route.
It's better to go with a real auto responder service like Aweber or GetResponse.
The reason is once you start to build up your list, you'll want to use it more. Now after awhile if you're sending emails from your own server and not watching spam, email service providers will begin to block your emails.
Using a service like Aweber and GetResponse work with the email companies to make sure this doesn't happen. They're pretty cheap too and have nice tools to increase your subscription rate.
I use GetResponse myself, but Aweber is said to be the best.
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