Subscription plugin Wysija
I would highly recommend the plugin to subscribe Wysija. It working vert well and support is perfectly.
If you have problems with subscribe and unsubscribe confirmation (blank pages) create file single-wysijap.php similar to single.php.
single-wysijap.php file can NOT contain breadcrumb code:
<div id="breadcrumb"> <?php if ( function_exists('cp_breadcrumb') ) cp_breadcrumb(); ?> </div>
regards