Hmm.. found why it doesn't work: The snippet above is written in the WordPress Editor and is placed on a (static) content page. Somewhere before that part there is a shortcode that shows posts from a certain category (announcements), which should be displayed as normal content in between two other text blocks (written in the editor).
When I remove the shortcode above that said text part, the plugin works fine and the email link is encoded.
This is the part where the shortcode gets the posts:
$return_string = '';
query_posts(array('orderby' => $order_by, 'order' => $order, 'cat' => $category_id , 'category_name' => $category_name , 'showposts' => $posts));
if (have_posts()) :
while (have_posts()) : the_post();
$content = get_the_content();
$content = apply_filters('the_content', $content);
$content = str_replace(']]>', ']]>', $content);
$return_string .= '<div class="listed-post">';
$return_string .= '<h2>'. get_the_title() .'</h2>';
$return_string .= $content;
$return_string .= '</div>';
Any ideas how I could fix that?