(1) Where an enactment authorises or requires a document to be served by post, whether the word “serve” or any of the words “give”, “deliver”, or “send” or any other word is used, the service of the document may be effected by prepaying, registering and posting an envelope addressed to the person on whom the document is to be served at his or her usual or last known place of abode or business and containing such document; and unless the contrary is proved, the document shall be deemed to have been served at the time at which such envelope would have been delivered in the ordinary course of post.