YOU’RE writing an e-mail to a group of friends – both guys and girls. You’re trying to come up with a friendly, informal greeting. A simple “Hello, everyone!” seems too plain. A “Howdy, ya’ll!” seems a little too country. “Hey, guys!” seems like it’s the best option. But wait! Although it was once the go-to mixed-gender greeting in the US, it has now begun to lose favor among women – and understandably so.