Abstract: A machine-learning classification system for a hosted data storage service classifies documents in storage domains of the hosted data storage service. A hosted data storage service can include isolated storage domains that are individually configured to provide domain access by an authorized entity for a domain and prohibit access to the domain by unauthorized entities. A machine-learned domain-specific classifier is associated with a storage domain and is configured to generate a classification label for documents of the entity associated with the respective storage domain. A training system is configured to generate a machine-learned domain-specific classifier using a subset of annotated documents from the selected storage domain.

Abstract: A cloud device is configured in an email transmission pathway. The cloud device receives an email attachment whose maliciousness status is determined to be unknown. The cloud device encrypts the email attachment and delivers the encrypted attachment to the recipient. When the recipient attempts to access the encrypted attachment, the cloud device re-determines the maliciousness status of the attachment. If the re-determined maliciousness status is benign, the cloud device allows the encrypted attachment to be decrypted and opened locally on the recipient's device. If the re-determined maliciousness status is still unknown, the cloud device provides a cloud-based viewing solution to the recipient using an isolation service.

Abstract: The disclosed computer-implemented method for encrypting files may include (i) detecting an event within a network that triggers an encryption of a file on the network, (ii) performing, in response to detecting the event, both encrypting the file to a file encryption key and encrypting the file encryption key to a public key of a source of the file, (iii) receiving, from a client, a file access request that includes the encrypted file encryption key, and (iv) transmitting, in response to determining that the client is authorized to access the file, a re-encrypted file encryption key to the client to enable the client to access the file. Various other methods, systems, and computer-readable media are also disclosed.