1. Non-transitory computer storage storing an executable component configured to provide functionality for selectively protecting attachment data addressed to a mobile device, the executable component comprising instructions that direct one or more computing devices to a process that comprises: receiving, from an enterprise resource, an attachment to a message, the message addressed to the mobile device; determining whether to encrypt the attachment based on one or more configurable access policies of an enterprise; and when a determination is made to encrypt the attachment: encrypting the attachment; causing transmission of the encrypted attachment to the mobile device in place of the attachment; encrypting an attachment key used to encrypt the attachment; and causing transmission of the encrypted attachment key with the encrypted attachment to the mobile device.