Legal Question in Criminal Law in Texas

They can leave the subpoena with her, but that is not effective service. There are a number of methods to get effective service, but what you describe would be insufficient. You can be served in person, or even by email if you acknowledge receipt of the subpoena. If you get a subpoena by email, you should not acknowledge receipt if you want to avoid effective service.

Failure to appear on a subpoena that was effectively served can subject you to contempt and the issuance of what is called a writ of attachment which is a type of arrest warrant.