function custom_easymail_auto_add_subscriber_to_list_by_post ( $subscriber, $user_id=false ) {
	global $post;
	if ( is_singular() && is_object($post) ) {
		switch( $post->ID ) {

			// List of post IDs and related lists
			case 1:
			case 2:
				$list_id = 1; // put the ID of mailing list
				break;
			case 3:
				$list_id = 2; // put the ID of mailing list
				break;			

			// etc etc ........
			
			// A default list
			default:
				$list_id = 3; // put the ID of mailing list
		}
		alo_em_add_subscriber_to_list ( $subscriber->ID, $list_id );
	}
}
add_action ( "alo_easymail_new_subscriber_added",  "custom_easymail_auto_add_subscriber_to_list_by_post", 10, 2 );