To view the raw delivery logs of a clean message, from the Quarantine+ page, select the "All clean mail" option, enter a string from either the From or Subject line of the message:
Once you have located the message that you want to view the delivery logs on, click on the "Logs" option located below the message:
The logs from the most recent delivery attempt will be shown:
If more than one delivery attempt has been made, a list of delivery logs will be presented so that you can view the logs on previous delivery attempts.
See also: Tracking down a message after it has been delivered to your mail server