Values.ComplaintSourceInformation about a Complaint event.
type nonrec t = {complaintSubType : ComplaintSubType.t option;Can either be null or OnAccountSuppressionList. If the value is OnAccountSuppressionList, SES accepted the message, but didn't attempt to send it because it was on the account-level suppression list.
*)complaintFeedbackType : ComplaintFeedbackType.t option;The value of the Feedback-Type field from the feedback report received from the ISP.
*)}