Summary - Bounced

Wrong address	The message had PERMANENT errors during delivery. These typically are wrong email addresses. After one or more unsuccessful deliveries the message is removed from the send queue, and the corresponding subscriber is unsubscribed.
Mailbox full	Mailbox is full. This message hasn't been delivered because the user's mailbox is temporarily exceeding its quota. These addresses should be removed from the Subscribers list only when the counter reaches a high number of errors compared with the number of deliveries.
Autoresponders	This is an automatic reply, usually due to the receiver's absence (e.g. Out Of Office, Vacation Message). NOTE: these messages do not always end up in the bounce mailbox; they can be sent directly to the sender's address, thus not being included in N:Bounce statistics.
Temporary errors	A temporary error: the delivery system found an error in the receiver's system, but it will try again. If the error persists, the system will give a Hard Bounce error.
Blocked emails	The message includes non-interpretable text parts. The message had PERMANENT delivery errors. The receiver's mail server refused the message for an unspecified reason. See error details to have additional information.

WL User Guide