Sendinblue - Automation Workflow - Order Confirmation not sending to guests

Hi

We've recently started using Sendinblue with our nopCommerce store. We're using it for some transactional messages, for newsletters and we've also setup Marketing Automation workflow.

One issue that I noticed when we setup Purchase Automation is that it sends the Order Confirmation to our registered customers without any issues, but when it comes to unregistered customers (Guests) it doesn't do anything, nothing appears in the logs and no tracking event is happening....

Is this by design or is this a feature that was forgotten to include in the plugin?

It would be quite bothersome to have to have Transaction email enabled for Order Confirmation as well as having the Automation workflow as it would mean our registered customers would be getting two different emails (One Transactional and one part of the Automation Workflow).....

We're using nopCommerce 4.20

Yep, it's by design.
Tracking and marketing automation only works for registered customers, since it requires the user's email and we cannot use billing address email for this.
But you can customize the plugin for your needs.