// Remove:
$content .= '<h3 class="mp_product_name"><a href="' . $permalink . '">' . esc_attr($product->post_title) . '</a></h3>';

//Add in it's place:
$content .= '<h3 class="mp_product_name"><a href="' . $permalink . '">' . esc_attr($product->post_title) . '</a> from ' . get_bloginfo( 'name' ) . '</h3>';