Peppol’s Next Big Shift: Message Level Status Becomes Mandatory

On 2 July 2026, OpenPeppol published a series of updates that will change how Access Points handle delivery confirmation across the Peppol network.

At the centre of these updates is Message Level Status (MLS) v1.1.0. OpenPeppol also introduced:

• Service Provider Operational Guideline on MLS v1.0.0
• Peppol Envelope Specification v2.0.2
• The first version of the Peppol Network Policy
• Code List v9.7

OpenPeppol has also organised dedicated sessions, including Open Dialogs, MLS Basics, and “MLS Impact on Existing APs and SMPs”, to help Service Providers understand and prepare for the changes.

Here is what MLS means, why it matters, and what Peppol Service Providers need to do.

What Is Message Level Status?

Peppol distinguishes between three different layers of status information as a message moves through the network:

• Protocol Status: Confirms compliance with Peppol eDelivery and PKI requirements, such as the AS4 signal message.
• Messaging Status: Confirms compliance with the Peppol Architectural Framework. This is where MLS applies.
• Business Status: Confirms whether the document complies with local or business rules, such as a Peppol BIS Invoice Response.

MLS sits between protocol status and business status.

It allows the receiving Access Point, known as C3, to inform the sending Access Point, known as C2, whether an incoming message was successfully processed and forwarded.

This status is separate from the validity of the underlying invoice or business document.

A positive AS4 acknowledgment only confirms that the message reached C3. MLS confirms whether C3 was able to process and forward it successfully.

MLS Migration Timeline

OpenPeppol has defined three key milestones for the MLS transition.

1 July 2026: Specifications Take Effect

The updated specifications become effective and the implementation period begins.

28 February 2027: MLS Receiving Capability Required

By the end of Phase 1:

• MLS receiving capability must be available in production.
• Service Providers must be able to register their MLS receiving capability in the SMP.
• The activation period for MLS sending begins.

31 March 2027: MLS Sending Becomes Mandatory

By the end of Phase 2:

• MLS sending becomes mandatory.
• The new Service Level Requirements become enforceable.

What Service Providers Need to Implement

During Phase 1, Service Providers are expected to:

• Build MLS sending infrastructure.
• Implement MLS queuing and retry mechanisms.
• Build MLS receiving infrastructure.
• Parse and evaluate MLS fields within the Standard Business Document Header.
• Register MLS receiving capability in the Service Metadata Publisher.

This is a significant engineering task. The implementation period may appear long, but queuing, retry logic, testing, production deployment, and SMP registration all require time.

New MLS Service Level Requirements

Two new Service Level Requirements define how quickly MLS messages must be handled.

SLR MLS-1: Sending

At least 99.5% of MLS messages relating to business documents under 10 MB must be sent within 20 minutes.

SLR MLS-2: Reception

At least 99.5% of MLS messages relating to business documents under 10 MB must be received within 25 minutes.

These thresholds are measured statistically over a monthly reporting period. They are not individual guarantees for every message.

A missing MLS within the first 25 minutes must not automatically be treated as proof that delivery failed. A positive AS4 acknowledgment already confirms that C3 accepted responsibility for the message.

The sending Access Point should not resend the original business document simply because the MLS response did not arrive within 25 minutes.

What Happens If No MLS Arrives?

The escalation process begins after 24 hours.

If MLS was requested unconditionally and no response has arrived after 24 hours, C2 should contact C3’s support team.

The contact may be made through:

• A known Service Provider contact point.
• Contact information published in the SMP endpoint.
• Contact information available through peppol.org as a last resort.

C2 and C3 should then coordinate the appropriate next steps directly.

All cases involving a missing MLS should be logged for operational monitoring and compliance evidence.

One MLS Response Per Document

Each received business document must generate either zero or one MLS response.

If C2 receives more than one valid MLS response for the same transmission, only the first valid response should be processed. Any later responses must be ignored.

Duplicate detection at the AS4 or transmission layer is expected to be handled separately.

Failure of Delivery Rejection Code

The Failure of Delivery, or FD, rejection code can only be used under specific conditions.

It may be used when:

• The incoming message is architecturally correct.
• C3 cannot permanently forward the message to C4.
• The rejection is caused by a non-business issue.

Even when an FD response is sent and the document is returned to C2, responsibility for resolving the underlying delivery issue remains with C3.

MLS Reporting Requirements

MLS messages count as Peppol Dataset exchanges and must be included in Transaction Statistics Reporting.

A separate Document Type Identifier must be used for MLS transactions.

However, MLS messages must not be included in End User Statistics Reporting. MLS is an exchange between Service Providers and does not directly involve end users.

MLR Is Being Phased Out

A separate OpenPeppol update published on 15 July 2026 introduced the “Peppol MLR Phase-Out v1.0.0” document.

The transition away from Message Level Response should therefore be monitored alongside the implementation of MLS.

Why MLS Matters

MLS closes an important visibility gap in the Peppol network.

Previously, a successful AS4 acknowledgment confirmed that the transport process had worked and that the receiving Access Point had accepted the message. It did not confirm whether the message had been successfully processed and forwarded.

MLS provides this additional confirmation.

For Access Points and their customers, this means:

• Better visibility into message delivery.
• Faster identification of forwarding problems.
• Fewer silent message failures.
• Clearer responsibilities between Access Points.
• Measurable network reliability.
• Better operational and compliance evidence.

What Access Points Should Do Now

The final enforcement deadline is 31 March 2027, but Service Providers should not wait until then.

Access Points should begin preparing by:

• Reviewing their current AS4 and message processing architecture.
• Scoping MLS sending and receiving requirements.
• Designing queuing and retry mechanisms.
• Updating message monitoring and logging.
• Preparing SMP capability registration.
• Updating Transaction Statistics Reporting.
• Testing duplicate response handling.
• Defining the 24-hour escalation process.
• Training operational and support teams.

For practical implementation purposes, Q4 2026 should be treated as the target for having the main MLS architecture and development work underway.

Conclusion

Message Level Status represents an important shift in the Peppol network.

It moves delivery confirmation beyond “the message reached the receiving Access Point” toward “the receiving Access Point successfully processed and forwarded the message.”

Once the new Service Level Requirements become enforceable in March 2027, MLS will become a central part of Access Point operations, monitoring, reporting, and support.

Service Providers that begin implementation early will have more time to test their infrastructure, complete SMP registration, and prepare for the new operational requirements.

Sources: OpenPeppol Message Level Status v1.1.0, Peppol Service Provider Operational Guideline on MLS v1.0.0, and OpenPeppol eDEC Specifications Change Log updates published on 2 July and 15 July 2026.