This answer comes from the Intercom Community forum. 👌

Your invoice notification emails are not useful if we are trying to get our finance system to process them automatically.

Please allow invoices, not just notifications, to be sent out automatically.

Great news. We've just released a feature, so invoices will now be sent as PDFs, attached to those notification emails.

Enable this from your Billing settings under Billing contacts and tick the option, "Attach pdf of invoice to the notification email".

See this thread and share your own feedback here on Intercom Community.