PHP script for Email list building?

I bet that someone has made it already and it's probably very easy but I don't know that much about PHP to do it on my own.
So I'm looking for a script that captures form submit value and saves it as a list in .txt file
If it's possible to save more info like IP it'd be even better.

This is for Email list building. I don't want to use getresponse or aweber or whatever to make my list. When it comes to mailing it's a different question.
Maybe database would do a better job?

Found a script. Just in case anyone is looking

<?php
$fails = "list.txt";
$valja = fopen($fails, 'a') or die("wtf");
$dati = $_GET['epasts'] . "\n";
if (fwrite($valja, $dati)) {
echo "success";
}
else {
echo "wtf";
}


?>