The free public scan reads what anyone can observe about your domain and homepage — including the signals that decide whether your own notification emails reach an inbox — and returns the priorities worth investigating first. If your notifications are going to spam, the email deliverability page explains what receivers are checking.
The message, the journey and the response time cannot be judged from outside. That is what the reviewed Digital Fitness Assessment is for: it combines what you provide with human review and returns your three priorities, each with the evidence behind it.
Onduu does not sell website fixes, so the diagnosis is not a quotation in disguise. Whoever fixes the cause — your team or an independent provider — starts from evidence.