Email bounce reason is "recipient blackholed"

Version 2

    Issue Description
    An email hard bounces with reason "551 5.7.0 [internal] recipient blackholed".  The person is automatically marked as Email Invalid as a result.


    Issue Resolution
    Blackholed addresses are those that Marketo have identified as spam traps, or those that have requested the Marketo Privacy team to block all Marketo originating emails.