Thanks for your feedback.
At my previous employer, we found a solution to extract the mirror page link per customer, of course only after the email had been sent. However, we also used Adobe Campaign Classic as a tool. I was hoping that AJO would offer a similar way to get the individual mirror page link. I'm not quite sure how this was technically implemented at the time, but in Adobe Campaign Classic you could view every email template that was sent in the profile (including personalisations) and I think the mirror page link was then extracted and exported from this.
Also you are right, that the mirror page link will expire (after 60 days) but that would not be a problem cause it should not be an endless archiving, but more a help for our customer service agents if a complaint arises.
Maybe someone else has an idea. We have also considered the BCC solution, but this is of course more complex than simply exporting a link.