Is there any case law for written replies to letters or emails satisfying service of process requirements?

Question

Hypo...

Bob is required to serve a pre-court proceedings’ notice [or complaint/other filing even] on Cob. Bob and Cob are both [U.S./California] citizens.

Bob sends all documents required to Cob in a regular email or letter neither of which constitute proof of service. However, Cob replies (1) addressing the letter by its title, (2) and expressly acknowledges receipt, in fact, acts upon the notice or even engages in continued exchange with Bob wherein Cob accepts liability for the subject matter Bob needed to serve the documents on Cob.

Questions

Is there any case law that would support that Cob was served upon the notice and his reply, acknowledgement, replies and/or acknowledgement of his liability which required the service constitute proof of service of process?

Is there any U.S. case for similar circumstances where a direct explicit reply to such letter or email containing all information to be served on another party would constitute proof of service of process if the reply comes from the party to be served?

My research so far...

The only law that explicitly considers replies as proof of services seems to be from South Australia:

"Email service in accordance with rule 42.2.

This means sending the documents as an attachment in PDF or Word format to an address used by the recipient and the recipient replying or actively acknowledging receipt of the email. However, a response generated automatically by the recipient’s email service is not considered a reply or acknowledgment of service [r 42.2 (3)]." Not unreasonable, is it?

Are there any exceptions per case law? Excused by the other parties conduct, etc.?

Case laws of interest:

Marchall v. Warwich (1998) 155 F. 3d 1027 - Court of Appeals, 8th Circuit

Answer 1

Are there any case law for written reply to letters or emails constitute proof of service of process?

More precisely, there is case law reflecting that the defendant's reply might be tantamount to waiving the entitlement to further --or to formalities of-- service. See Hwang v. Chu, (CA Court of Appeals, unpublished, Sept. 2016) ("[I]f the acknowledgment is so worded as to evidence an intention to waive further service, it partakes of the nature of a waiver and is legally sufficient to confer jurisdiction over the person of the defendant", citing Smith v. Moore Mill & Lumber Co., 101 Cal.App. 492, 495 (1929)).

More conclusive is the fact that Cob "expressly acknowledges receipt" because that enables compliance with section 417.10(d) of the CA Code of Civil Procedure ("Proof that a summons was served on a person within this state shall be made [...] [b]y the written admission of the party").

The Marshall opinion you brought up is one of many instances of incredibly vexatious judiciary. The court pretends that "delivery of a copy of the summons and complaint" might not be sufficient for "charg[ing] the defendant with notice of a pending action" (citing Volkswagenwerk Aktiengesellschaft v. Schlunk, 486 U.S. 694, 700, brackets added). Marshall at 1031 dwells on "the risk that the defendant never received notice". However, such concern is moot in that controversy. That is because Warwick's act of removing the case to district court implies that he was well aware of there being a pending action against him.

Likewise, the substance of how Cob "acts upon the notice or even engages in continued exchange with Bob" might reinforce the finding that the notice Cob received was sufficient for making him aware of the pending action.

Answer 2

A response is proof of delivery and notice. The filing of an answer with a court to a complaint in a civil action waives the defense of improper service of process, unless the responsive pleading raised that issue immediately. But no other form of response to a complaint improperly served (such as responding to it with an email) waived the defense of improper service of process.

But a response is not necessarily proof of service sufficient to trigger an obligation to respond to court process, which requires strict compliance with the means of delivery required by law, and proof of service on the defendant in that manner.

In contrast to court process (like a summons or a subpoena) many other notices that must be given by law do not have to be served in accordance with the specific rules that govern the service of these documents and proof of delivery and notice may be enough.

For example, if a contract provides that notice must be given by certified mail and the party gives notice by regular mail and gets a response instead, the judge could find that the notice by regular mail was substantial compliance with the contract term and an immaterial breach of the contractual requirement. But the judge couldn't do that in the case of service of a summons to commence a court case.

Now, if one makes duly diligent attempts to service of process by an authorized means and those attempts are unsuccessful, one can seek permission of the judge to service process by an alternative means authorized on a case by case basis. If the judge has evidence that the defendant already has actual notice of the document to be served, the judge might authorize service in this particular instance, by regular mail or email or text message, or some other means that might not be authorized generally, and that decision would almost certainly be upheld against a due process challenge on appeal, because the legal standard for substituted service is that it is reasonably calculated to provide actual notice, and there is proof of actual notice.

But for means of service of court process that are not expressly authorized by law to be effective, a judge has to issue an order in advance permitting that method to be used.