I don't trust online reviews that much, but some of these may be relevant:

- https://uk.trustpilot.com/review/runbox.com

- https://cyberinsider.com/email/reviews/runbox/

- https://uk.pcmag.com/cloud-services/94763/runbox

- https://old.reddit.com/r/mail/comments/1qdlyrh/runboxcom/