When sending an encrypted email you will occasionally receive an Undeliverable Notice. This usually occurs when the recipient you are sending to has an Out of Office or Automatic reply setup on there end.
Here is how this would happen:
- Message is sent and triggers encryption and sent to secure portal
- Recipient receives a notification from firstname.lastname@example.org to log onto their portal to retrieve message
- Recipient’s mail client auto replies to email@example.com which forwards on a copy of the auto reply to the original sender along with an Undeliverable notice
You can see this by opening the Undeliverable Notice and looking for the attached Auto Reply.