After installing Nutsmail, I get a blank page in my browser

This is usually caused because the config.php or config_local.php file has an error in it somewhere. Try searching for lines that are missing characters: ' or " or ; at the end or beginning. A properly formatted setting would be:

$setting = 'configured text';

or

$setting = "configured text";

the exceptions being numerical values and true/false settings which should look like this:

$setting = true;

or

$setting = 120;