Any person who knowingly sends, delivers or causes to be sent or delivered to any employee of the postal company for the purpose of being transmitted as a telegram any message or communication which has been wilfully and without due authority altered or which purports to be signed or sent by any other person without that person's consent, or who wrongfully signs any telegram with the name of another person without that person's consent or with the name of some fictitious person or who wilfully and without the consent of the sender alters any telegram or writes, issues or delivers any message or communication which purports to be a telegram received through a telegraph office but which was not so received, is guilty of an offence and liable on conviction to a fine or to imprisonment for a period not exceeding two years or to both a fine and such imprisonment.