Creating a "send" button in WordPress

I’m working on a newsletter plugin for wordpress. I want to use a post button for sending the posts. But how can i achieve this? The code that i have right now is as follows:

add_action('manage_nieuwsbrief_posts_custom_column', 'nwsbrf_custom_nieuwsbrief_column', 10, 2);

function nwsbrf_custom_nieuwsbrief_column($column, $post_id) {

	global $wpdb;

	$getcategories = $wpdb->get_results( $wpdb->prepare("SELECT * FROM wp_nwsbrf_couple INNER JOIN wp_nwsbrf_categories WHERE wp_nwsbrf_couple.category_id = wp_nwsbrf_categories.category_id AND ID = %d", $post_id) );

	foreach ($getcategories as $categorie) {
		switch ($column) {
			case 'cat':
			echo $categorie->category_name;
		break;
		}
	}
		switch ($column){
			case 'send';
			echo '<input type="submit" class="button button-secondary button-small" name="send_post" value="Verzenden">';
		break;
	}
}

As you can see i’m using send_post as the name for my button. I want to use this button for sending my mails. Can someone please explain me how i can make a handler for it?