Hi there,
I think there is a logic error in the back in stock flow. Every now and then we see that a suppressed user signs up for the queue, but then does not receive an email because he is suppressed. In my understanding, the flow should be sent regardless of the status of the user (active or suppressed), as this is a separate signup and no newsletters are sent on it.
I had already contacted the support with this problem, but unfortunately no solution could be found. Do you have similar problems? Have you found solutions how to work around the problem?