USPS can deliver court papers, and mail can sometimes be a legally valid service method. Whether it completes service depends on the court, document, defendant, and governing rules. Buying certified mail does not by itself turn any mailing into valid service.
Initial service needs the right rule
A summons and complaint follow rules different from later papers in an existing case. In federal court, Rule 4 includes specific service methods and can incorporate applicable state-law methods for certain defendants. It is therefore too broad to say mail can never serve an individual in federal court.
For example, the Eastern District of Michigan’s self-represented guidance describes certified mail with restricted delivery and return receipt as a service option under the applicable framework. That court-specific guidance should not be exported to every state or defendant. [1]
A waiver request is different from service
Federal procedure allows requesting that a qualifying defendant waive formal service. The Northern District of California explains the package, including the complaint, notice/request, waiver form, and prepaid return method. Mailing the request does not mean a waiver has been obtained; the defendant must return the signed waiver. [2]
If the defendant does not waive, arrange a valid service method before the governing deadline. Do not assume an unanswered certified letter automatically starts the defendant’s response period.
Special defendants require special attention
Government defendants, agencies, corporations, minors, and people outside the United States can require different recipients and procedures. Service on a business employee is not automatically service on the organization. A green return receipt may prove delivery without proving that the legally required person received the papers.
- Identify the applicable rule and any incorporated state rule.
- Use the required mailing type and correct recipient.
- Preserve tracking, receipts, and any signed waiver.
- File the required proof or return of service.
Compare who may sign for certified mail and interference with federal process servers. Postal authorization to sign is not necessarily legal authorization to accept lawsuit service. If service is challenged, use the actual documents and rule rather than relying solely on the tracking website’s “delivered” status.
Primary sources
Sources checked: October 31, 2026.