Integrations
Connect Billnado to OkiOki via Mailbox
Configure your personal OkiOki address in Billnado and check document receipt and automatic Peppol delivery of sales invoices.
Updated on October 22, 2026
Mailbox delivers invoices and credit notes from Billnado to your business’s personal OkiOki address. You need access to the Billnado administration and an OkiOki account that supports document submission. Agree with your accountant how received documents will subsequently reach the accounts.
Step 1: find your personal OkiOki email address
In OkiOki, open your preferences and personal OkiOki email address (Voorkeuren > OkiOki e-mailadres in the Dutch interface) and copy the address. Check that you are in the correct business account. Use this document address as the destination, rather than the general support address or your own login address.
You do not need to connect your entire personal mailbox to OkiOki for this delivery method. Billnado delivers exported documents directly to the specified OkiOki address.
Step 2: check automatic Peppol delivery
In OkiOki, check the e-invoice sending options under your account settings (Je account > Instellingen in Dutch). OkiOki has an option to send submitted UBL sales invoices through Peppol immediately. Align this choice with how you invoice your customers from Billnado.
Note: if OkiOki automatically sends submitted sales UBLs through Peppol, the document may also reach your customer after the Billnado export. Disable automatic sending if you already deliver the invoice from Billnado and only use OkiOki for accounting.
The OkiOki guide to external UBL files describes this behaviour and states that file submission for this feature requires an OkiOki Smart subscription. Ask your accountant to confirm that your account supports the required delivery.
Step 3: configure Mailbox in Billnado and save
In the correct Billnado administration, open Settings > Integrations > Accounting. Select Mailbox under Accounting software.
| Billnado fields, for both PDF and UBL | OkiOki destination |
|---|---|
| Email for sales invoices | Use your business’s personal document address and check automatic Peppol sending. |
| Email for sales credit notes | Use the same document address and have recognition as a sales credit note confirmed. |
| Email for purchase invoices | Use the same document address for supplier invoices. |
| Email for purchase credit notes | Use the same document address and have recognition as a purchase credit note confirmed. |
Copy the confirmed address into the eight PDF and UBL fields. Billnado sends one file per document: preferably a suitable UBL, otherwise the available PDF.
Choose Deferral period for automatic export and match Maximum attachment size to OkiOki’s receiving limits. Billnado defaults to 2 MB. Agree Only send UBLs that are PEPPOL-compliant for sales documents with your accountant; this setting does not determine whether OkiOki subsequently sends the received document again.
Check the business, document address and further processing in OkiOki. Choose Save.
Step 4: check one document in OkiOki
Choose a document not yet in OkiOki. Check it using the eye icon in the Billnado document list and choose Export. This actually sends it to OkiOki.
Find the document in OkiOki and compare its number, amount and purchase or sales classification. Ask your accountant to check how credit notes are recognised and whether the document is forwarded to the accounts. For sales, also check that it has not unintentionally been sent to your customer again.
Daily use and troubleshooting
Agree which channel collects each document. OkiOki can also retrieve the same invoice from a connected mailbox, cloud folder or another channel. Check whether the document is already present before exporting it again from Billnado.
If a UBL is rejected, check the document message in OkiOki. OkiOki does not modify externally submitted UBL files itself. For missing documents, also check the personal address, your subscription and the file size.
Mailbox does not retrieve postings, corrections or payment statuses from OkiOki into Billnado. Select None under Accounting software and save to disable future automatic exports. Documents already in OkiOki are not retrieved.