wanted to highlight a new feature that just recently launched that enhances the capabilities of Office 365 Message Encryption. As you may recall, Office 365 Message Encryption released this past February, and replaced the functionality previously known as EHE (Exchange Hosted Encryption).
Essentially, Office 365 Message Encryption enables users to send encrypted emails to anyone at any email address. It utilizes server-side policy rules created by the administrator to determine what emails get encrypted, so there is no need for additional software/hardware.
Read more at source: http://blogs.technet.com/b/uspartner_ts2team/archive/2014/10/13/one-time-passcode-for-office-365-message-encryption.aspx