When creating a new Email Campaign, there are 2 options available to you. You can either get emails from a Custom List, or get them from an Email List.
If you haven't already setup an email list, you can click the Custom List option to add contacts manually to this campaign.
There are a number of different filters you can use to narrow down your email list. You can choose between:
Contacts, which will auto-add all your contacts.
Leads, which will auto-add all of your Lead contacts.
Shoots, which will auto-add all of your Shoot contacts.
Galleries, which will auto-add all of your Gallery contacts (Note: this reads the contacts from the attached Shoot).
Gallery Guests, which will auto-add all of your signed up contacts from your Gallery email lists.
Each one of these sections has further filters you can use to narrow down your desired email list. It will let you choose between significant dates on the jobs (like inquiry dates, shoot dates, etc.), the Shoot Types, the Statuses on the jobs, and more!