We have created a custom offer recommendation model for emails. When we are sending an email to a single recipient, everything is correct - expected offers are included in the email. When we are sending emails to multiple recipients, all of them receive the same offer. We analyzed the situation and it seems that there is some hash calculation that is used the same for all recipients and thus same offers are returned for a whole batch.
That should be bug and not how offer recommendations in emails should work, right? It must be possible to send out personalized offer recommendations instead same set for all?
What means "optimized algorithms" for recommendations in emails? What it technically does? Could it be a reason/bug why we are receiving same offers for all email recipients?