This example adds a short reminder below the spam entries settings.

add_action( 'frm_spam_entries_settings', 'my_frm_spam_review_note' );
function my_frm_spam_review_note( $frm_settings ) {
	echo '<p class="howto">Review the Spam tab weekly and mark real entries as not spam.</p>';
}

This example adds a checkbox and saves it when the global settings are saved. Formidable checks the request and passes the posted values to the frm_update_settings action.

add_action( 'frm_spam_entries_settings', 'my_frm_spam_digest_setting' );
function my_frm_spam_digest_setting( $frm_settings ) {
	printf(
		'<p><label><input type="checkbox" name="my_frm_spam_digest" value="1" %s /> Send the team a weekly list of new spam entries</label></p>',
		checked( get_option( 'my_frm_spam_digest' ), '1', false )
	);
}

add_action( 'frm_update_settings', 'my_frm_save_spam_digest_setting' );
function my_frm_save_spam_digest_setting( $params ) {
	update_option( 'my_frm_spam_digest', empty( $params['my_frm_spam_digest'] ) ? '0' : '1' );
}

Read the saved value in your own code with get_option( 'my_frm_spam_digest' ).