curl --request GET \
  --url https://api.pocketflows.com/sent_emails/{id} \
  --header 'Authorization: Basic <encoded-value>'

{
  "id": "<string>",
  "created_at": "<string>",
  "customer": "<string>",
  "subject": "<string>",
  "sent_at": "<string>",
  "failed_at": "<string>",
  "failed_reason": "<string>",
  "sendgrid_message_id": "<string>",
  "paubox_message_id": "<string>",
  "postmark_message_id": "<string>"
}