Funny things happen. A customer just tells me that he sees sent newsletters under history of the respective person but always with the same, absolutely unrelated contact. If the email is opened there is of course no trace of this person. And no, they do not keep the text of the emails.

I then checked mine and there I see the same. For two out of three newsletters everything looks good (nothing in history), only the third one has an entry in everybody's history panel with always the same unrelated contact related to it.

I'm running 5.1b (also for the latest newsletter), the customer is on 5.0h

Any ideas?