When serving a claim form, the Civil Procedure Rules specify recognized ways to do it. The valid method among the options is to send the claim form by first-class post to the defendant’s address for service. This method is allowed and creates deemed service two days after posting, which gives a clear point at which the claim is considered served. The other options don’t fit standard service rules. Submitting via social media isn’t a recognized method of service under CPR. A public announcement isn’t a valid method unless substituted service is ordered by the court in a situation where ordinary service can’t be achieved. Faxing without any acknowledgment does not constitute valid service, since proper service must occur by a formal method with a deemed or actual acknowledgment of receipt, or via a court-approved substituted method if needed.