Well, I believe there's a thin line of difference b/w transactional and operational emails; the former is sent as a part of the transaction initiated by the person - e.g., order confirmation, order updates, etc. However, the latter are sent to communicate crucial information that everybody on your list needs to hear. In the Marketo world, users refer to both types of emails as Operational emails as Marketo doesn't have a setting for setting emails to Transactional, all non-marketing emails that should ignore Unsubscribed and Marketing Suspended statuses are marked as operational emails. AFAICT per the GDPR, both transactional and operational emails can be sent without explicit consent from the recipient (i.e., with the Operational checkbox in the Email setng checked), as long as they are genuinely necessary for the transaction or operation of the service. However, for marketing or promotional emails, explicit consent is required.