Clean email form input in PHP

clean.php

function cleanInput($input) {
    // Pass the $_GET, $_POST or $_REQUEST array
    $output = array();

    foreach ($input as $key=>$value) {
        $o = $value;

        // Make sure it's within the max length
        $o = substr($o,0,256);

        // Tidy up line breaks
        $o = preg_replace('/\n{2,}/', "\n\n", $o);
        $o = nl2br($o,FALSE);

        // Strip any odd characters
        $o = preg_replace('/[^A-Za-z0-9\. -\!\?\(\)\<\>\@]/', "", $o);

        // Put the data back in the array
        $output[$key] = $o;
    }

    // Return the array
    return $output;
}