Copying database to local machine

We are attempting to migrate some mail. We need to open a database in a Notes client. We don’t want to be working with live mail files so we plan to make copies of the live files.We created and signed the database on the client, copied a mail file from the server on to the client, and then attempted to open the mail file from the local disk. We got a message that the client was not “trusted”. Did we miss a step? How do you copy a mail file from the server to a local drive and open it?