My manuscript is as polished as it's ever going to be so I'm ready to begin querying. I found an agent in a pretty big agency who would be a great fit. The agency itself accepts only submissions by post, and by email only if you know an agent personally. The agent I'm targetting says on her bio that she is open to preliminary contact by email. What does this mean? Does this mean a traditional query or just an introduction with a view to sending a full query/synopsis?