Which of the following would most likely not allow an email to be processed by Mimecast?

Blocked Sender Policies in Mimecast directly prevent emails from specific senders or domains from being processed. When a sender is classified as blocked, any email originating from them will be rejected at the gateway level before it can enter the Mimecast environment for further processing. This means that these emails will not undergo antispam checks, content filtering, or any other processes that would typically be applied to incoming emails.

In contrast, Permit Sender Policies explicitly allow emails from defined senders to pass through Mimecast filtering without any restrictions. A Bi-Directional Policy allows emails between specified parties in both directions, while an ARMed Policy (Advanced Risk Management) is designed to evaluate the risk associated with incoming emails, but does not inherently block them. Therefore, these options would still allow for processing of emails, whereas a Blocked Sender Policy unequivocally prevents processing altogether.