Isode provides messaging infrastructure products for military messaging over STANAG 4406 and Internet Protocols as well as gateways between military messaging systems and between military and non-military messaging systems. Isode products are ideal for deployment in both standard and constrained bandwidth environments. On this page we look at Isode products for military email solutions, for military instant messaging and multi-user chat please see the page on Military XMPP.

What Isode Provides

Isode provides servers for military messaging, deployed in a range of environments:

  • Isode's M-Switch MTA can be deployed as either an X.400 MTA, for formal military messaging using STANAG 4406, or for use with Internet protocols (for formal and informal military messaging over SMTP).
  • M-Switch MIXER provides a gateway between SMTP and X.400 (inc STANAG 4406) messaging systems it can also be configured as a full ACP145 gateway.

Isode products feature support for message precedence, digital signatures using S/MIME for SMTP messages and STANAG 4406 ed2 signatures, security labels and security label mapping, message tracking for reliable messaging and operation over constrained bandwidth networks.

Formal Military Messaging using STANAG 4406 (& STANAG 4406 Annex E)

STANAG 4406 is the NATO Standard for formal military messaging, replacing the older ACP127 specification. Used for both Strategic and Tactical messaging, STANAG 4406 has a number of special protocols to support tactical messaging, in particular to support very low bandwidth links such as HF radio (STANAG 4406 Annex E) and to support receivers in Emission Control (EMCON) mode who can receive but not send data.

Isode is a market leading provider of STANAG 4406 messaging infrastructure. Details are given in the STANAG 4406 Military Messaging solutions page, including gateways to ACP127.

Instant Messaging and Multi-User Chat using XMPP

STANAG 4406 and SMTP are standards for store and forward messaging (email). Military communication is making increased use of real time (instant) messaging, both 1:1 and multi-user chat. XMPP is the Internet Standard for real time messaging and presence, and is gaining increasing military usage.

Isode M-Link XMPP server is available for both standard XMPP communications and, using an Optimized Server-to-Server protocol, for XMPP over low bandwidth links including HF Radio. M-Link provides control of messages using security labels associated with the messages the security clearances of the users.

For further information see Isode's Military XMPP Solutions page.

Formal Military Messaging over SMTP

There appears to be benefit to using SMTP for formal messaging. Isode has described what is needed to achieve this in the whitepaper [Military Messaging (MMHS) over SMTP] and has initiated work on a number of specifications needed in support of this. The first of these is "Registration of Military Message Handling System (MMHS) header fields for use in Internet Mail" which has been approved for publication as an RFC. This defines fourteen message headers, such as "MMHS-Primary-Precedence:" to extend a standard SMTP message. A number of implementations of this specification have now been made. NATO are considering adoption of this specification.

Informal Messaging using SMTP

SMTP (Simple Mail Transfer Protocol) messaging is ubiquitous. SMTP messaging is used widely by military organizations. This use is generally referred to as "informal messaging" to distinguish it from formal messaging used for command and control. For more information on Isode's SMTP messaging products see Isode Internet Messaging Servers overview page.

Gateways with STANAG 4406

Isode provides two gateways between SMTP and STANAG 4406. These both provide full mappings from STANAG 4406 onto the new MMHS over SMTP capabilities:

  1. M-Switch MIXER provides a gateway between SMTP and standard STANAG 4406.
  2. It can also provide a full ACP145 gateway, which provides STANAG 4406 edition 2 digital signatures and security labels and is designed to interconnect national military networks operating according to different profiles. For further details see the whitepaper [ACP145: Isode Support of International MMHS Gateways].

Gateways are discussed in more detail on the STANAG 4406 Military Messaging page.

Applications for Military Radio & Satellite

Many Isode applications are optimized for use over Radio, Satellite and other multicast and potentially low quality/performance links. Although this functionality may have general application, Military organizations are the primary target of these applications, and a number of protocols specified for military use are key to Isode's product set.

Our Applications for Military Radio & Satellite solutions page gives an overview of the products and management tools that Isode provides for Radio and Satellite networks, giving a communication network oriented view of the Isode product set.


Message precedence is critical for military operations over slower networks. Isode M-Switch supports this, with controlled grade of delivery for the six military precedence values. It also supports MINIMIZE, so that processing of lower precedence messages can be suspended. This capability can be controlled by clients using the MMHS-Primary-Precedence header. Isode is leading activity to standardize precedence handling for SMTP networks, see the IETF Draft "Simple Mail Transfer Protocol extension for Message Priorities".

Digital Signatures

Isode supports digital signatures of messages using S/MIME for SMTP messages and STANAG 4406 ed2 signatures. M-Switch can verify message signatures, strip message signatures, and add signatures to messages. This provides high flexibility for digital signature use in environments with mixed capabilities and protocols.

Security Labels

Isode provides comprehensive support for Security Labels and Security label mapping in M-Switch. For information on M-Switch use of security labels see the M-Switch product page. For information on Isode general security label capability see the Isode Security Policy, Security Label and Security Clearance Infrastructure & Management product page.

Tracking and "Fire and Forget"

To provide reliable messaging, delivery reports and read receipts can be used. These enable message tracking to record problems and to detect when messages are delayed. This can be monitored by Isode MConsole.

This capability can be used to provide a "fire and forget" capability, where the message sender can be confident that once a message is sent that it will be delivered and acted on, which is vital when messaging is used for command and control. For further information see the whitepaper [Using Message Acknowledgements for Tracking, Correlation and Fire & Forget].

Constrained Bandwidth

Operation over constrained networks is vital for many military deployments. Isode offers a SMTP messaging solution based on the ACP 142 military specification. This provides optimized communication for both point to point and multicast networks, and operation in EMCON (Emission Control or Radio Silence). This can be operated over IP networks such as Satcom and fast radio links. Isode also supports direct operation of STANAG 5066 to give optimal performance for HF Radio.

For more details on protocol stacks, M-Switch operation over constrained networks and a list of relevant whitepapers see the M-Switch: Constrained Networks & HF Radios product page.

Further information

Isode whitepapers on this subject can be found from our whitepaper section on Military Messaging, including:

  • Using Message Acknowledgements for Tracking, Correlation and Fire & Forget
    This whitepaper looks at how tracking end to end message acknowledgements can improve service reliability for mission critical messaging. This is achieved by enhancing message tracking services and providing information on messages being delivered and read. It then describes how this can be extended to provide a "Fire and Forget" quality service, using operator alerts and guaranteed action points (GAP). The paper also shows how these capabilities are provided in Isode's M-Switch product.
  • Military Messaging (MMHS) over SMTP
    Military Message Handling (MMHS) is specified in STANAG 4406, which operates over the X.400 Messaging protocols. This whitepaper looks at how MMHS could be provided over SMTP noting where this can be done with existing standards, where there is active work to define standards, and where there are currently no standards. It concludes with a summary of what is needed to make MMHS over SMTP a reality that can meet operational requirements.
  • The Architecture of Isode's STANAG 4406 Annex E Solution
    Military Messages often need to be transferred over low bandwidth networks, in particular HF Radio and Satellite Networks. Isode provides ACP 142 and STANAG 4406 Annex E as a part of its M-Switch X.400 product. This paper describes Isode's approach to implementing these protocols, and how this addresses basic and advanced operational problems, management approaches and integration with other components as part of a larger solution.