Scott,

 

Yeah, this will be making a comeback in a "dot" minor...16.1 or 16.2. We're having to work out exactly how to do it in the new interface.

 

For now, you can go to your contacts, hide all the groups apart from the one you want to email, select all those contacts, then click the Actions (...) button and use the Send Email option. That will send an email to all the contacts you have selected.