LetterAgent
Mail physical letters by just asking your AI assistant.
Home > Guides > Proof of service by mail
Proof of service by mail is a signed statement, filed with the court, that a copy of a document was mailed to the other side. It lists what was sent, to whom, at what address, and on what date. Without it, the court has no record that the other side received the papers.
This is general information, not legal advice.
A court case runs on a record, and service is part of that record. Filing a document with the clerk is only half the job: the other side must also get a copy, so they have a fair chance to respond. Proof of service is how the court verifies that second half happened. Judges check it before ruling on motions, because ruling against a party who never got the papers would be unfair and could be overturned.
The proof also starts clocks. Many response deadlines run from the date of service, not the date of filing. A filed proof with a clear mailing date lets everyone, the court, the other side, and you, agree on when those clocks started. An unclear or missing proof invites disputes about timing, and timing disputes are exactly the kind of side argument that delays the real issues.
The person who actually mailed the copy signs the proof. That person states, under penalty of perjury or by declaration depending on the court, that they placed the document in the mail as described. Courts commonly require the server to be at least 18 years old and not a party to the case. That rule is why lawyers' offices have staff handle routine mailings, and why a party who mails their own papers can see the service challenged.
This rule surprises self-represented litigants more than any other service rule. It feels natural to drop your own filing in the mailbox and sign a form saying you did. But the neutrality requirement exists so the statement comes from someone with no stake in whether service is believed. If no one else is available, a friend, a colleague, or a process server can do the mailing, and the cost of that help is small compared with a challenged service.
| Element of the proof | What it must show | Common mistake |
|---|---|---|
| Document served | The exact title of each document mailed | Writing "court papers" instead of the document names |
| Recipient | The name of the party or their lawyer | Mailing to the party when they have a lawyer of record |
| Address | The mailing address used, matching the court record | Using an old address after the party moved |
| Date and method | The date of mailing and that it went by first-class mail | Leaving the date blank or signing days later from memory |
| Server signature | Signature of a non-party adult who did the mailing | The party signing their own proof |
Most courts publish a proof of service form for their jurisdiction, often called a certificate of service or declaration of service. The form asks for the case name and number, the documents served, the names and addresses served, the date and method of service, and the server's signature. Use the court's own form whenever one exists, because a home-made version risks omitting a field that court's clerks check. Keep a copy of the signed proof with your copy of the filed document, so you can produce it if service is ever questioned months later.
The usual sequence has three steps, and the order matters. First, file the original document with the court. Second, mail a copy to the other side, or have someone do it for you. Third, file the proof of service with the court. Some courts allow the proof to ride along with the original filing when service happens the same day, but the proof cannot honestly be signed before the mailing happens. Signing a proof for a mailing that has not yet occurred is a serious error, and courts treat false statements about service harshly.
Mailing and filing also interact on deadlines. A document filed on Monday but mailed on Friday may still be timely for filing, yet late for service if the other side's response clock runs from service. When a deadline is tight, file and serve on the same day, and keep the mailing receipt alongside the file-stamped copy. Certified mail with a return receipt adds a second layer of evidence: the green card, or its electronic equivalent, shows delivery to the address, while the proof of service shows what was sent.
No, and that distinction matters. Proof of service shows a document was mailed to the correct address on a stated date. It does not show the recipient opened it, read it, or understood it. Courts accept mailing as service because the law treats delivery to a proper address as sufficient notice, not because anyone verified reading. If the other side claims they never got the papers, the court weighs your proof, the mailing receipt, and the address record, and a clean proof usually wins that argument.
LetterAgent mails letters to US and Canadian addresses, and it can mail case-related correspondence. But a proof of service must be signed by the person who did the mailing, so a service that mails for you does not replace the signed certificate. If you use a mailing service for case correspondence, keep its mailing records and have the certificate signed by someone who can truthfully state how the mailing was made.
Ready to mail it? Send your letter with LetterAgent: describe it to your AI assistant, approve the exact quoted price, and it is printed and mailed.
LetterAgent is a working name. Prices include print, postage, and our service fee. US prices in USD, Canadian prices in CAD (Canadian prices exclude applicable sales tax, added at checkout). Currently in private testing.
Need help? Ask your assistant: it can check a job's status any time. If it ever can't handle something: hello@getletteragent.com