My main problem is that spammers hacked the "sender unknown" error message long ago and use it to spam me (they send mails pretending to be me, so the error mes

My main problem is that spammers hacked the "sender unknown" error message long ago and use it to spam me (they send mails pretending to be me, so the error message gets delivered to me). So I had to filter them all away. I wish Thunderbird's spam filter would check if I actually sent the message the error message refers to.