Rule 1420 A writing may be authenticated by evidence that the writing was received in response to a communication sent to the person who is claimed by the propo…

If you send a letter, email, or other message to a specific person, and they write back, that response can be used as proof that they are the one who wrote it.

For example, if you send an email to John Smith and receive a reply, the fact that the reply came in response to your message helps show that John Smith actually wrote it. You do not need a signature or other direct proof of who the author is. The back-and-forth nature of the communication itself serves as evidence.