Courtney,
The behavior you are describing is related to "out of band" bounce processing. This is not the standard way most email receivers process mail and it displays as having delivered and THEN bounced. This is because the mail server accepted the email initially and sent Marketo an "delivered" status notice. Then after processing the email the mail server determined it could not deliver the email and then returned a bounce. Because Marketo recieved two seperate events related to the delivery you will also see both.
Most email networks determine whether the email address is deliverable before accepting the message so in the event of a bounce we only receive the failure and not the "delivered" status notice too.
The Soft Bounce status means that the message was not delivered for what may be a temporary reason.
Thank you,
Kiersti
Manager, Deliverability and Privacy Team
Kiersti Esparza