Additional checks are added.

git-svn-id: https://plugins.svn.wordpress.org/thinkit-wp-contact-form/trunk@794642 b8457f37-d9ea-0310-8a92-e5e31aec5664
Additional checks are added.

git-svn-id: https://plugins.svn.wordpress.org/thinkit-wp-contact-form/trunk@794686 b8457f37-d9ea-0310-8a92-e5e31aec5664