What is a “vacation response” vs “temporary bounce”?

Vacation responses and temporary bounces are fundamentally different:

Vacation response:

Message was delivered successfully. User set up automatic reply. Indicates active, managed account. Comes from user's mailbox. Contains personal message.

Temporary bounce:

Message was not delivered. Server-generated failure notification. Indicates infrastructure issue. Comes from MAILER-DAEMON or postmaster. Contains error codes.

Key distinctions:

Delivery status: Vacation = delivered; bounce = failed. Source: Vacation = mailbox; bounce = server. Action required: Vacation = none; bounce = retry or suppress.

Why distinction matters:

Vacation responses should not trigger suppression. Bounces may require list action. Misclassification loses valid subscribers.

Vacation response is a friendly note from a delivered mailbox. Bounce is notice of failed delivery.