Sending emails is easier when you have an address book! For example, you want to send an asset by email. When you click the share button, a window with the email details pops up. In the right corner of the email field you can find a small book icon. Click it and you'll open the Address Book menu.
In that menu you can choose or add contacts, whether it's a certain person or a group. Or both. You can also create a new group, based on your custom selection. After you're satisfied with your selection, hit the Apply button and proceed with the email details.