Peppol MLS or Message Level Status is a technical status message that your buyer's service provider (C3 in Peppol) sends back to the service provider that sent your e-invoice (C2) to report what exactly happened to the document. It is not the buyer's commercial response to the invoice. According to Peppoli MLS specification v1.1.0 MLS is intended as a trust check between two service providers, not to confirm whether the buyer actually received, approved, or paid the invoice. MLS global rollout begins July 1, 2026, but for service providers, active MLS submission will only become mandatory March 31, 2027. Until this deadline, the lack of positive status is completely normal, not an error.
Does AP mean that the buyer received and approved the invoice?
No. AP indicates that your buyer's service provider has verifiable confirmation that the document has been processed by the final recipient (C4). This confirmation could be, for example, a confirmation of receipt provided via a software API. According to specification AP cannot be used when the document is sent to C4 by email. In this case, the only possible positive status is AB. AP is therefore strong technical proof that the invoice arrived at the buyer's system, not proof that the accountant saw the invoice or started paying.
What do RE, AP and AB mean?
RE says that the document did not reach C4 processing at all. More common reasons there is a schema or rules error, a virus, a broken attachment, a file that is too large or a permanent transmission error. AP means verifiable confirmation that the document reached the C4. AB means that the C3 forwarded the document to the C4, but it cannot be confirmed whether it arrived. This is the case, for example, in the case of email, file transfer or local storage from which the document is later read. If the C3 experiences a temporary error, AB is used and the transmission continues. This does not automatically mean a permanent rejection corresponding to the RE.
Why does a correctly sent invoice not have a positive status?
The most common cause is not a bug, but a default setting. The specification determines default mode FAILURE_ONLY: if your sent envelope does not have the MLS_TYPE=ALWAYS_SEND mark, the buyer's service provider will only send back a negative RE response, but will not send a positive AP or AB. So the lack of status does not mean that the invoice is lost. It usually means that no one has requested a positive confirmation.
What to ask your e-invoice software before 2027
The service provider must have reception capacity in production no later than 28 February 2027, before active sending From March 31, 2027 becomes mandatory. Ask your software or operator three things: do they already support MLS reception, will AP and AB statuses become visible to you in the user interface, and will they fulfill the requirements for smaller documents? Peppoli in network policy The speed given is that 99.5% of MLS messages should arrive within 20–25 minutes. And remember: MLS does not replace Estonian in the Accounting Act The agreement with the transaction partner regarding the invoice format and acceptance conditions is stipulated. The substantive approval is still given by the buyer, not the Peppoli network.
FAQ
Does AP mean that the buyer received and approved the invoice?
No. AP is a technical confirmation that the document has reached the final recipient (C4) for processing, not a commercial approval of the buyer. AP does not prove that the accountant saw the invoice or started paying.
What do the Peppol MLS statuses RE, AP and AB mean?
RE – The document did not reach C4 for processing (schema error, virus, broken attachment, too large file). AP – Verifiable confirmation that the document reached C4. AB – C3 forwarded the document, but cannot confirm its arrival (e.g. by email).
Why does a correctly sent invoice not have a positive status?
The most common reason is the default setting FAILURE_ONLY - if the envelope does not have MLS_TYPE=ALWAYS_SEND, the service provider will only send back a negative RE, not a positive AP or AB. No one has requested a positive confirmation.
When will Peppol become mandatory for MLS service providers?
The service provider must have reception capability in production no later than February 28, 2027. Active MLS sending will become mandatory on March 31, 2027.