Assuming your e-mail addresses are in file.txt:
<?php
$fp = fopen('file.txt', 'r');
if(false !== $fp) {
$i = 0;
while(!feof($fp)) {
$data = fgets($fp, 4096);
$i++;
}
echo "You have $i e-mail addresses";
}
else {
echo "can't open text file";
}
fclose($fp);
?>