When an automation sends an email (for example a New Membership Started welcome), each send is listed under Marketing › Emails › CAMPAIGNS › Automations, near the bottom of the Email menu.
What do the columns mean?
Send To: who the automation sent to: Users (your team) or Contacts (your customers). Point at the small i icon beside it to see the recipient.
Subject: the email's subject line.
Status: Sent, with a count underneath such as Sent 1 or Opened 1.
Campaign Date and Date: when the automation ran.
Use Per Page and the page numbers at the bottom to see older sends.
How is this different from the other folders?
CAMPAIGNS › Sent lists campaigns you sent yourself.
CAMPAIGNS › Scheduled lists campaigns waiting to go out.
CAMPAIGNS › Automations lists sends triggered by an automation.
CAMPAIGNS › System lists campaign sends made by Stackably itself.
To see every single email an automation sent, including its delivery status, use All Mail with the Source filter set to Automation.