Lists one kind of event of a transactional email, chosen by type, oldest first:

• opened: each time the recipient opened it (TransactionalOpenResource)
• clicked: each click on a tracked link (TransactionalClickResource)
• bounced: the receiving server rejected it, with the reason (TransactionalBounceResource)
• complained: the recipient reported it as spam (TransactionalComplaintResource)

Bounces and complaints arrive minutes to days after the email was sent; the email.bounced and
email.complaint webhooks push them as they happen. Events are recorded once per email, not per recipient:
for an email with cc or bcc addresses they can't tell which address bounced or complained.