This is the mail system at host mail.zapf.in. I'm sorry to have to inform you that your message could not be delivered to one or more recipients. It's attached below. For further assistance, please send mail to postmaster. If you do so, please include this problem report. You can delete your own text from the attached returned message. The mail system <physiksprecher(a)physik.rwth-aachen.de&gt;: host mx1.rz.rwth-aachen.de[137.226.78.57] said: 550 #5.1.0 Address rejected. (in reply to RCPT TO command) <karbach(a)uni-wupperatl.de&gt;: Host or domain name not found. Name service error for name=uni-wupperatl.de type=AAAA: Host not found <afeld(a)uni-postdam.de&gt;: Host or domain name not found. Name service error for name=uni-postdam.de type=AAAA: Host found but no data record of requested type <Eric.Runge(a)TU-Ilmenau.de&gt;: host a2221.mx.srv.dfn.de[194.95.232.182] said: 550 5.1.1 <Eric.Runge(a)TU-Ilmenau.de&gt;: Recipient address rejected: undeliverable address: host piggy2.rz.tu-ilmenau.de[141.24.186.70] said: 550 5.1.1 <Eric.Runge(a)TU-Ilmenau.de&gt;: Recipient address rejected: User unknown in relay recipient table (in reply to RCPT TO command) (in reply to RCPT TO command) <jan.wierig(a)ovgu.de&gt;: host b2501.mx.srv.dfn.de[194.95.235.9] said: 550 5.1.1 <jan.wierig(a)ovgu.de&gt;: Recipient address rejected: undeliverable address: host mx3.ovgu.de[141.44.1.69] said: 550 5.1.1 <jan.wierig(a)ovgu.de&gt;: Recipient address rejected: User unknown in virtual alias table (in reply to RCPT TO command) (in reply to RCPT TO command)