I figured out a very weird side effect: I sent an email campaign to 1.500 contacts & leads - all mails were send successfully. Afterwards, I found out that the history has been added with one new entry: “email sent (the mail from the campaign) connected to one contact (the first which is assigned to my user in contacts)” in every account. The contact connected to the email entry is the same in every history of an account. I hoped to fix this issue by deleting this contact but the effect was that this history entry still exist but is connected to another contact (the following first contact, which is assigned to me). This contact is again equal in every account history.
I am using SuiteCRM Version 7.7 based on Sugar Version 6.5.24 (Build 509). I tried already a quick repair.
I am looking forward for any hint or support.