Every order required by its terms to be served, every pleading subsequent to the original complaint unless the court otherwise orders because of numerous defendants, every paper relating to discovery required to be served upon a party unless the court otherwise orders, every written motion other than one which may be heard ex parte, and every written notice, appearance, demand, offer of judgment, designation of record on appeal, and similar papers shall be served upon each party except those in default for failure to appear. Parties so in default shall be given notice of pleadings asserting new or additional claims for relief against them by summons or warning order issued thereon as provided in Rule 4.