I apologize and acknowledge this.
I didn't want to burden paid support unnecessarily; I thought someone would have experience and respond.
Unfortunately, that didn't happen, so I ended up creating a duplicate support ticket.
This is a special case that was actually caused by an incorrect import of users into the list and subsequent sending of the campaign.
I have already solved it through logical reasoning and thanks to the fact that acymailing provides a list of users to whom the newsletter was delivered in its statistics.
Thank you.
