The short answer

An Access Point is the certified service that gets your documents onto the network and off it again. An SMP is the directory entry describing what a participant can receive and where to send it. The SML is the global index that tells a sender which SMP to ask.

Together they are why you can invoice a company you have never dealt with, on a network you have never configured for them, and still have it arrive correctly.

The problem the directory solves

Start with what would happen without one.

If you wanted to send a structured invoice to a new customer and there were no directory, you would need to ask them a series of questions first. Which format do you accept? Which version of it? Where should I send it, technically? Who operates your receiving system? Then you would configure your system for those answers, and repeat the whole exchange for the next customer.

That is exactly the arrangement traditional point to point document exchange requires, and it is why it scales so badly. Every new trading relationship is a small project.

Peppol's answer was to publish the answers to those questions in a directory that any sender can query automatically, in the moment, without asking anyone. That directory is what the SMP and SML provide between them.

The clever part of Peppol is not the document format. It is that you never have to ask the recipient how to reach them.

What an Access Point actually does

"Connects you to the network" undersells it. There are five distinct jobs, and providers differ in how well they do the ones that are not the network transmission itself.

1
Conversion
Takes your invoice in whatever shape your system produces it and builds the structured document the specification requires. This is where most of the project effort sits, because your data has to be complete enough to build from.
2
Validation
Checks the document against the rules before it goes anywhere, including country specific rules where they apply. A document that fails does not get sent, which protects the buyer from receiving something unusable.
3
Recipient lookup
Queries the directory to find out where the recipient's documents go and what they accept. This happens per document, so a recipient who changes provider is handled without you doing anything.
4
Secure transmission
Delivers the document to the receiving Access Point over the network's secure transport, with both ends authenticated by certificates issued through the Peppol authority structure.
5
Outcome handling
Returns whether delivery succeeded, and surfaces failures in a form somebody can act on. This is the job that varies most between providers and matters most once you are live at volume.
Certification is not optional. Access Points are certified and hold network issued certificates. That is what allows two providers who have never dealt with each other to trust a document between them. It also means the list of providers is a known, finite set rather than anyone who fancies it.

What an SMP publishes

The Service Metadata Publisher holds the record for a participant. Conceptually it answers three questions about one business.

Who are you
The participant identifier, combining a scheme code with the organisation number
→
Your address on the network
Stable, and belonging to your business rather than to your provider
What can you receive
Document types and the specific specification versions you support
→
Sender knows before sending
Avoids delivering a document the recipient cannot process
Where does it go
The endpoint of the Access Point that receives on your behalf, plus its certificate
→
Delivery and trust
Sender knows both the destination and that it is genuinely yours

The practical consequence people miss: if you are not published, you are not reachable. A business can be fully connected for sending and still invisible to anyone trying to send to them, because publishing is a separate act from connecting. If a customer tells you they cannot find you on the network, this is almost always why.

Where the SML fits

There are many SMPs, operated by many providers around the world. So a sender faces one more question before it can query anything: which SMP holds the record for this participant?

The Service Metadata Locator answers that. It is the single global index for the network, and it does one job: given a participant identifier, tell the sender which SMP to ask.

What happens when you send
01
SML query
Which SMP holds the record for this participant?
→
02
SMP query
What do they accept and where does it go?
→
03
Validate
Check the document against the rules for that type
→
04
Deliver
Transmit to the receiving Access Point and record the outcome

All four steps happen in the moment of sending, per document. Nobody configures a trading partner in advance, and that is the entire point.

Why this matters when choosing a provider

Understanding the layers changes the questions worth asking. Every certified Access Point does the network part correctly, because certification requires it. Differentiation is elsewhere.

Worth asking
  • What happens when a document fails validation, and who sees it
  • How failures are surfaced: a dashboard, an alert, or an email nobody reads
  • Whether they connect to your finance system or hand you a file to upload
  • How registration and publishing are handled, and by whom
  • What switching provider later would involve
Less useful to ask
  • Which transport protocol they use, since it is fixed by the network
  • Whether they can reach a particular recipient, since any participant is reachable
  • Whether they support the invoice document type, since all of them do

The right hand column is where a lot of vendor comparison energy goes, and none of it distinguishes anyone. The left hand column is what you will care about in month three.

The failure modes worth knowing

Three things go wrong in practice, and knowing the layer each sits in makes them much faster to diagnose.

Recipient not found. The lookup returned nothing for that identifier. Either the identifier is wrong, or the recipient has not been published. Neither is fixable at your end beyond confirming the identifier with the customer.

Document type not supported. The recipient is published but their entry does not list what you tried to send, or lists a different version. This is a real mismatch rather than an error, and it usually needs a conversation with the buyer about what they actually accept.

Validation failure. Your document did not satisfy the rules. This is the common one by a wide margin. It is entirely at your end and almost always a missing or malformed field rather than anything structural. The fix belongs in your source data, which is why the data quality work matters more than the connection.

We operate as a certified Access Point

Registration, publishing, format mapping and connection into Xero, QuickBooks or your ERP, handled as one piece of work rather than four suppliers.

Talk to the team

Common questions

What is a Peppol Access Point?
A certified provider that converts your invoice to the required format, validates it, looks up the recipient, transmits it over the network and reports the outcome. Every participant reaches the network through one.
What is an SMP?
A Service Metadata Publisher. It holds the directory entry describing which document types a participant accepts and the endpoint where their Access Point receives them. Publishing an entry is what makes a business reachable.
What is the difference between SMP and SML?
The SMP holds detail about one participant. The SML is the single global index that tells a sender which SMP to ask. The SML answers where to look, the SMP answers what and where.
Do I need my own SMP?
Not usually. Your Access Point provider publishes your entry. Operating an SMP is a provider level undertaking with its own certification requirements.
Can I change provider later?
Yes. Your identifier belongs to your business, and switching means updating the directory entry to point at the new endpoint. Worth asking how a provider handles it before signing rather than after.
Peppol Access Point E-invoicing Technical