As home user, they don't allow me to open a case.

Even if it is basically a bug report.

You may be right, I don't think my fetchmail is set to delete if it can't fetch, but then the astaro did not even delete it from the target pop3 server, even though it prefetched normally and deleted the rest of the mails.

quite strange.

I sent you an email, but I'm not absolutely sure that the email I attached is the whole email, I took that one from the astaro mail spool, it could be, that it did not fetch the whole mail due to some error.