Service information for Office 365 Message Encryption


Applies to: Exchange Online, Exchange Online Protection, Office 365

Topic Last Modified: 2016-01-14

The following table provides technical details for the Office 365 Message Encryption service.


Service details Description

Client device requirements

Encrypted messages can be viewed on any client device, as long as the HTML attachment can be opened in a modern browser that supports Form Post.

Encryption algorithm and Federal Information Processing Standards (FIPS) compliance

Office 365 Message Encryption uses the same encryption keys as Windows Azure Information Rights Management (IRM) and supports Cryptographic Mode 2 (2K key for RSA and 256 bits key for SHA-1 systems). For more information about the underlying IRM cryptographic modes, see AD RMS Cryptographic Modes.

Supported message types

Office 365 Message Encryption is only supported for items that have a message class ID of IPM.Note. For more information, see Item types and message classes.

Message size limits

Office 365 Message Encryption can encrypt messages of up to 25 megabytes. For more details about message size limits, see Exchange Online Limits.

Exchange Online email retention policies

Exchange Online doesn’t store the encrypted messages.

Language support for Office 365 Message Encryption

Office 365 Message encryption supports Office 365 languages, as follows:

  • Incoming email messages and attached HTML files are localized based on the sender’s language settings.

  • The viewing portal is localized based on the recipient's browser settings.

  • The body (content) of the encrypted message isn't localized.

Privacy information for OME Portal and OME Viewer App

The Office 365 Messaging Encryption Portal and Viewer App privacy statement provides detailed information about what Microsoft does and doesn't do with your private information.