CPR 6.3 permits service by personal service, first class post or other next-business-day delivery, leaving the document at a permitted address, fax or other electronic means in accordance with Practice Direction 6A, or any method the court authorises. CPR 6.5 defines what personal service means for an individual, a partnership and a company.
Service is proved by a certificate of service under CPR 6.17 — and, where the claimant served the claim form, that certificate must generally be filed within 21 days of service. The date service takes effect is fixed by the deemed service rules in CPR 6.14 for claim forms and CPR 6.26 for other documents, not by the date the recipient says they read it.