Who is this for?
Generally, SMP data is maintained by providers of electronic invoicing services. They use an SMP to publish their customers' data, so that other trading entities can find them on the PEPPOL network.
Why not run my own SMP?
That is certainly an option. The advantage of using an existing SMP is that you need not worry about maintaining yet another service, so that you can focus on your core services.
What is PEPPOL?
See What is PEPPOL?
How does PEPPOL work?
Can I see which recipients are registered on this SMP?
Not directly. However, you can search for a specific recipient by its identifier on tools such as the Simplerinvoicing test tool or Philip Helger’s Participant Information tool. Such tools will consult the data on the Peppol network, and if necessary, this SMP.
Additionally, some recipients are registered on the Peppol Directory, where you can also search by company name.