Legal Question in Family Law in California

It depends on whether she will cooperate or not. If she will sign a Judicial Council form "Appearance, Stipulations and Waivers," after you file, and she will either mail it to the court with a first appearance fee, or send it back to you to file, you never have to serve her. If you and/or she would prefer that she just default, but she is still cooperative, you can send her the papers by mail with a "Notice and Acknowledgment of Receipt" form. She then signs and returns it, and it's the same as if she was personally served. If she will not cooperate, it gets a lot more complicated, and California may not even have jurisdiction if she contests it. In that case you need an attorney with international divorce experience.

It is my understanding that if documents to be served by mail are to be served outside the state, they must be served by certified or registered mail, with return receipt requested.

Additionally, you are going to have to check the Hague Convention on extraterritorial service, which may have additional requirements. A copy of the convention can be found online, and in the annotated portion of Federal Rule of Civil Procedure, rule 4.