My counterparty is registered on Hermes but OkiOki says I cannot send invoice over Peppol to them?

OkiOki does not support Hermes for the moment as Hermes is probably going to be phased out. For more information check the website of BOSA (Dutch / French).

On top of that Hermes is not a ‘regular’ Peppol access point and invoices cannot be send to Hermes in a ‘regular’ way. For sending invoices over Hermes you would also need en email address of your counterparty and a language.

Companies who are registered on Hermes can easily register themselves on an access point (like e.g. OkiOki). They do not need to unregistered themselves from Hermes.