Welcoming me home

I got home from work yesterday and this is what I found greeting me home. He (or she - how do you tell the sex of a dragonfly?) was sitting on the wall right between the door and the mailbox. It stayed there even after I was all up in its face to take pictures, and even after I opened the door, and it was still there when I left 45 minutes later. From head to tail, it was 10cm long!