SMP, SML and Peppol Directory: how Peppol finds a recipient

Before an invoice can travel over Peppol, the sender's access point has to find out where the recipient receives its documents. It does so in two lookups. The SML (Service Metadata Locator), a central DNS service, says which SMP (Service Metadata Publisher) holds the recipient's details. The SMP, run by the recipient's provider, says which document types the recipient accepts and to which access point they must be delivered. The Peppol Directory is a separate, optional search index of business cards that plays no part in routing.

This reference explains how the three fit together, what each result proves and how OrdoGrid uses them. For the step-by-step check of a customer and the usual causes of “not found”, see Check whether a Belgian customer can receive invoices on Peppol. For identifier formats and the mod-97 check, see Peppol ID explained.

SML, SMP and Directory at a glance

Dynamic discovery

The way a Peppol access point finds, at the moment of sending, where to deliver a document: it asks the SML which SMP holds the recipient's ID, then asks that SMP for the address that accepts the document type. Nothing is set up per customer in advance.

In the four-corner model, your access point (corner 2) runs this discovery for you (corner 1) and delivers to the recipient's access point (corner 3), which passes the invoice to your customer (corner 4). Only providers write to the SML and the SMP; a business never edits them itself.

How a sender finds your customer, step by step

1. Build the participant ID. The sender takes the recipient's identifier: a scheme code, a colon and a value, for example 0208:0999887777, where 0208 means Belgian enterprise number. The value is not case-sensitive.
2. Hash it. The access point lowercases the ID, computes its SHA-256 hash and encodes it in Base32 without the trailing = signs, which gives a DNS label of fixed length.
3. Ask the SML. It queries the DNS name made of that hash, the scheme iso6523-actorid-upis and the SML zone. Under SML specification 1.3.0, in force since 1 November 2025, the answer is a U-NAPTR record for the service Meta:SMP holding the address of the recipient's SMP. No record means the ID is not registered in that environment.
4. Ask the SMP. The access point requests the metadata for the exact document type it wants to send, for example the Peppol BIS Billing 3.0 invoice. The SMP returns the receiving access point's address, the transport profile (AS4), its certificate and, optionally, activation and expiry dates. Senders must ignore an entry that is not yet active or has expired. An SMP may redirect the request to another SMP, but only one level deep.
5. Deliver. The sending access point delivers over AS4 to that address, using the certificate it has just received, and the receiving access point passes the invoice on.

Invoices and credit notes are separate document types in the SMP, so a recipient can be reachable for one and not the other. Peppol BIS Billing expects receivers to support both.

What the DNS lookup looks like

For technical readers, this is the production lookup for the identifiers in the worked example below. Any DNS tool can run the query; for this fictitious number it returns no record.

Participant ID     0208:0999887777
SHA-256, Base32    rjtk4m7ohrai7xkohzgw6eys7z3xmeftxm4xfckvlqtp6v4so3uq
DNS name (NAPTR)   rjtk4m7ohrai7xkohzgw6eys7z3xmeftxm4xfckvlqtp6v4so3uq.iso6523-actorid-upis.participant.sml.prod.tech.peppol.org

Participant ID     9925:BE0999887777
SHA-256, Base32    zqbxprwc6l2ypul5n2aqmbehihns4acomxhdsoxq3yhxs7rbihea

The same company under its VAT number hashes to a completely different name. That is why 0208 and 9925 are two separate registrations: one can exist without the other.

One ID, one SMP: what follows from it

OrdoGrid does not support migration keys: if another provider holds your registration, that provider must deregister you before OrdoGrid can register you. See Switch Peppol access point or provider without losing invoices.

What each lookup result proves

FPS Finance points businesses to lookup.peppol.org, OpenPeppol's lookup service, where you type 0208: followed by the enterprise number. It reads what is currently published, which is why OpenPeppol introduced it alongside the asynchronous Directory. FPS Finance warns that it does not show whether an organisation can also send.

A registration also has a legal meaning: according to FPS Finance, being published on Peppol as an invoice recipient counts as agreement to receive structured invoices (B2B FAQ, question 9).

How OrdoGrid uses these registers

OrdoGrid connects to Peppol through a certified access point. Its Peppol screens are in French in every interface language; labels are quoted exactly, with a translation.

When you send

OrdoGrid has no Peppol ID field on clients. When you click Envoyer (send) on an invoice or credit note, or the globe button Envoyer à Peppol (send to Peppol) in the list, it starts from the N° de TVA (VAT number) of the client on that document.

1. For a Belgian client, it looks up 0208: plus the ten digits in the SML, then 9925: plus BE and the digits.
2. If the SML gives nothing, it searches the Peppol Directory, then asks its own access point (Belgian clients only).
3. It addresses the document to the first ID it finds. For foreign clients, it tries the schemes it maps to the client's country.
4. The check runs again on the server when the document is actually sent.

OrdoGrid does not show which source answered or which ID it found. The list button's confirmation window shows Client inscrit sur Peppol (client registered) or Client non inscrit sur Peppol (client not registered). It does not show a technical failure separately: if the check fails, it also shows Client non inscrit sur Peppol, together with an error notice. In that case, retry later.

OrdoGrid's check confirms a registration; it does not read or show the document types in the customer's SMP. If that SMP has no entry for your document, the send cannot be delivered and the row in Peppol → Outbox ends in Erreur (error) instead of Traité (network delivery completed): see Peppol delivery status.

A tick does not prove reachability either: it can rest on a Directory card alone. If lookup.peppol.org shows no SML entry for the customer's ID, the send is likely to end in Erreur; ask the customer to have its provider fix the registration.

When you receive

1. On Réception Peppol (Peppol reception), OrdoGrid shows whether your own number is already on the network: Pas encore trouvé sur le réseau Peppol (not found yet), Déjà inscrit sur le réseau Peppol (registered with another provider), Déjà présent sur Peppol via notre access point (present through our access point) or Référencé sur Peppol, access point non vérifié (listed on Peppol, access point not verified). OrdoGrid decides who receives from the SMP that the SML names for your ID (without an SML answer, from its access point's own lookup), never from a Directory card alone; the last, grey state means it found you but could not verify which provider holds your ID. If the check itself fails, the page also shows Pas encore trouvé sur le réseau Peppol, together with an error notice: reload the page before you activate reception.
2. Activer la réception (activate reception) registers 0208: plus your ten-digit enterprise number and declares reception of the BIS Billing 3.0 invoice and credit note, Invoice Response, MLR and the self-billing invoice and credit note. OrdoGrid registers under 0208 only.
3. If another provider already receives for you, choose Continuer en envoi seul (continue send-only): you send through OrdoGrid and keep receiving where you are. When the SML names another provider's SMP for your ID, activation is greyed out and OrdoGrid refuses it; to receive in OrdoGrid, that provider must first release the ID.
4. In Peppol → Statut (status), Réception (Inbox) shows Enregistré (registered) and the date under “Depuis le” (since). Libérer la réception (release reception) deregisters your ID at OrdoGrid's access point; sending remains possible.
5. The Annuaire Peppol (Peppol Directory) panel on that tab reads Votre entreprise est référencée dans l'annuaire Peppol (listed) or Votre entreprise n'est pas encore dans l'annuaire Peppol (not listed yet). Despite its name, it uses the same lookup chain as sending, starting with the SML. When you are listed, it shows your Identifiant Peppol (Peppol ID) and, when known, Access point de réception (receiving access point): Notre access point (ours) or Autre prestataire (another provider). For a Belgian company registered under 0208 it also shows Nom enregistré (registered name) and Pays (country). If the panel lists Documents supportés (supported documents), check that Facture (invoice) and Note de crédit (credit note) both appear; otherwise check on lookup.peppol.org that both invoice and credit note are listed.

OrdoGrid has no Peppol test mode: every check and every send uses the production network. Setting up both directions is covered in Set up Peppol in OrdoGrid.

Worked example: an ID under 9925 only, and no credit-note reception

Bureau Claes BV, an IT consultancy in Leuven, starts working for Transport Maes NV in Antwerp, enterprise number 0999.887.777 (check: 09998877 divided by 97 leaves 20, and 97 − 20 = 77). Both are VAT-registered and established in Belgium. Bureau Claes invoices through OrdoGrid.

1. 2 October, before the first invoice. On lookup.peppol.org, 0208:0999887777 returns nothing. 9925:BE0999887777 returns Transport Maes NV with one document type: the BIS Billing 3.0 invoice, no credit note.
2. Reading the result. The SML has an entry for the VAT-number ID only, and the SMP lists invoices only. Transport Maes can receive F-2026-0214 but not a credit note, and its registration lacks the 0208 ID that Belgian providers must register.
3. 5 October, sending. In OrdoGrid, the send popover opened by Envoyer shows Envoi électronique via Peppol, ticked: behind the scenes, the 0208 lookup found nothing and the 9925 lookup found the entry. After Sauvegarder & Envoyer, the invoice goes to 9925:BE0999887777, and in Peppol → Outbox the row moves from En file (queued) to Traité.
4. Same day. The bookkeeper emails Transport Maes's accounts team: “Your Peppol registration lacks 0208:0999887777 and credit-note reception. Please ask your Peppol provider to add both.” The dated lookup screenshot is attached and filed.
5. 12 October, credit note. Two consultancy hours were not delivered. Before sending NC-2026-0009, the bookkeeper checks again: 0208:0999887777 now lists invoice and credit note. OrdoGrid finds 0208 first and sends the credit note there; the row reaches Traité.
6. Result. In the Settlement panel of F-2026-0214, Credits shows €229.90 and Outstanding €2,190.10 (€2,420.00 − €229.90).

Had the credit note gone out on 6 October, OrdoGrid's check would still have passed, because the 9925 entry existed. The customer's SMP had no credit-note entry, though, so the send would have ended in Erreur. The fix sat with the customer's provider, not in the credit note.

Production, test and the 2026 SML move

• Two separate networks. Production and test have their own certificates and their own SML zone: participant.sml.prod.tech.peppol.org and participant.sml.test.tech.peppol.org (the T-SML, formerly SMK). An ID registered only in test cannot be found from production. See Peppol test versus production: what to check before a live send.
• A new SML operator in 2026. OpenPeppol took over the SML from the European Commission. Providers had to move SMP registrations to the new SML by 31 May 2026 and switch their lookups by 31 August 2026. The old Commission addresses are not redirected and are being decommissioned.
• What it means for you. Nothing to change as a business: the migration is your provider's job. If lookups that used to work started failing around those dates, ask your provider whether its migration is complete.

Edge cases and common mistakes

Evidence to keep

These are recommendations; no rule prescribes this list.

• New business customer: a screenshot or PDF of the lookup.peppol.org result, with date, ID searched and document types listed. Note the outcome in the client's Notes field in Base Clients (client list).
• Customer not reachable: the dated lookup with no result under 0208 or 9925, and your message asking the customer to register. It shows why the invoice did not go via Peppol.
• Your own registration: the Statut tab showing Enregistré with its date, and your provider's confirmation. When switching, keep the old provider's deregistration date.
• Failed send: the Outbox status, the date, and what was fixed before the retry.

FAQ

What is the difference between SMP and SML?

The SML is one central DNS service for the whole Peppol network: for each participant ID it points to the one SMP that holds its details. The SMP belongs to the recipient's provider and lists, per document type, the access point that receives it. Senders ask the SML first, then the SMP.

Is the Peppol Directory authoritative?

No. Routing never uses it: the Directory indexes business cards that providers publish voluntarily, with a delay. Many registered businesses have no card. To see what is currently published, use lookup.peppol.org, as FPS Finance recommends.

Can two providers receive invoices for the same Peppol ID?

No. Each participant ID is registered with exactly one SMP, so one provider controls where its documents are delivered. Switching needs either a migration key from the old provider or a deregistration before the new registration; OrdoGrid supports only the second route.

Do I need to be registered in the SML to send invoices?

No, sending works without a registration of your own. But a business within the Belgian obligation must also be able to receive structured invoices, which requires a registration with some provider. In OrdoGrid, choose Continuer en envoi seul if another provider already receives for you.

How long after registration can suppliers find us?

There is no official publication time. The SML entry usually appears quickly but depends on the provider; a Directory card can follow later or not at all. Check your ID on lookup.peppol.org rather than waiting for the Directory.

Does OrdoGrid show which document types my customer accepts?

No. OrdoGrid confirms that the customer is registered under 0208 or 9925, not which document types its SMP lists. Check lookup.peppol.org for the BIS Billing invoice and credit note.