This article explains whether or not you can recover emails in the Blocked Traffic section of HES Mail Tracking.
Recovering blocked mails is not possible because these are not stored anywhere in the data center. These are explicitly blocked by the service because they are listed in the spam databases.
To know more about the database that HES/HES - Inbound Filtering uses to block networks sending spam, visit the IP Reputation section of your HES/HES - Inbound Filtering web console.
For detailed information on the databases, go to IP Reputation > Settings page.