The contact form requires full PHP mail support and it sounds like your web host may have disabled some of this functionality.
You could perhaps contact your web host and ask if they would allow full PHP mail support on your hosting account (including the fifth parameter to the function which seems to currently be disabled).
Otherwise, you could try the following (although I do not know if it will work).
(1) Open the 'showkase/admin/plugins/contact/master/contactcore/class.phpmailer.php' file in a plain text editor.
(2) Change line 631 from:
$result = @mail($to, $subject, $body, $header, $params);
... to:
$result = @mail($to, $subject, $body, $header);
This should ensure that the fifth parameter ($params) is not used in the PHP mail function.