Notices returned un-served to be delivered through other means under sec. 37C prior to ex-parte proc

Excise & Customs : Where notice sent by post is returned with postal remarks 'left', same must be tried to be served as per section 37C(1)(b) or as per section 37(1)(c) by affixing a copy on notice board of adjudicating authority; and if that is not done, consequential proceedings ex parte are invalid