Mail not send, but no error report

Hi there,

certain mails are not send, because the smtp server refuses them as they have wrong sender-adresses.

Session transkript only says:
smtp:none:none://localhost:25

It is OK, that the smtp-server refuses to send, but I think post-smtp should send an error message in this case. But there is no …

In the mail-log, the mail is marked as “sent”, although it’s not.

Any Idea how to get informed, if mails are not send?

Best regards

Uli