You can send a event invite to everyone, or to specific groups of contacts.
By default, the newsletter group will send to everyone in your database. When you add a contact, they are added to this group for you. Contacts can unsubscribe though.
You can create the email in the system, or import it from another email design package. Mailchiump integration and Constant Contact integration.
The system keeps a history of sent emails. You can see undeliverable, read counts and link clicking statistics. You can drill into these and get details of the contacts making them up.
This video gives on overview of inserting a registration link in an email, advertising an event, the registration page and exporting registrations