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 <ing(a)fs.un-sand.de&gt;: Host or domain name not found. Name service error for name=fs.un-sand.de type=AAAA: Host not found <fs-infotech(a)faveve.uni-stuttgart.de&gt;: host mx01.int.stuvus.uni-stuttgart.de[129.69.139.72] said: 550 5.1.1 <fs-infotech(a)faveve.uni-stuttgart.de&gt;: Recipient address rejected: Recipient does not exist (in reply to RCPT TO command) <fachschaftphil(a)gmx.de&gt;: host mx01.emig.gmx.net[212.227.17.5] said: 550 Requested action not taken: mailbox unavailable (in reply to RCPT TO command) <fsr_ff(a)haw-hamburg.de&gt;: host hawhamburg-de0i.mail.protection.outlook.com[104.47.11.138] said: 550 5.4.1 Recipient address rejected: Access denied. AS(201806281) (in reply to RCPT TO command) <fsr_hwi(a)haw-hamburg.de&gt;: host hawhamburg-de0i.mail.protection.outlook.com[104.47.11.138] said: 550 5.4.1 Recipient address rejected: Access denied. AS(201806281) (in reply to RCPT TO command) <fsr_information(a)haw-hamburg.de&gt;: host hawhamburg-de0i.mail.protection.outlook.com[104.47.11.138] said: 550 5.4.1 Recipient address rejected: Access denied. AS(201806281) [FR2DEU01FT020.eop-deu01.prod.protection.outlook.com 2024-01-08T12:30:49.035Z 08DC0F8F84A031B9] (in reply to RCPT TO command) <fsr_oet(a)haw-hamburg.de&gt;: host hawhamburg-de0i.mail.protection.outlook.com[104.47.11.138] said: 550 5.4.1 Recipient address rejected: Access denied. AS(201806281) (in reply to RCPT TO command) <fsr_pug(a)haw-hamburg.de&gt;: host hawhamburg-de0i.mail.protection.outlook.com[104.47.11.138] said: 550 5.4.1 Recipient address rejected: Access denied. AS(201806281) [FR2DEU01FT020.eop-deu01.prod.protection.outlook.com 2024-01-08T12:30:49.035Z 08DC0F8F84A031B9] (in reply to RCPT TO command) <fsr_wirtschaft(a)haw-hamburg.de&gt;: host hawhamburg-de0i.mail.protection.outlook.com[104.47.11.138] said: 550 5.4.1 Recipient address rejected: Access denied. AS(201806281) (in reply to RCPT TO command) <fachschaft(a)matwerk.net&gt;: Host or domain name not found. Name service error for name=matwerk.net type=AAAA: Host not found <fsr_nt(a)haw.hamburg.de&gt;: host mx2.ondataport.de[141.91.162.203] said: 550 5.1.1 <fsr_nt(a)haw.hamburg.de&gt;: Recipient address rejected: User unknown in relay recipient table (in reply to RCPT TO command) <fachschaft_lehramt(a)pse-stuttgart-ludwigsburg.de&gt;: host mxex2.tik.uni-stuttgart.de[129.69.192.21] said: 550 5.1.1 <fachschaft_lehramt(a)pse-stuttgart-ludwigsburg.de&gt;: Recipient address rejected: undeliverable address: host exchange.ad1.uni-stuttgart.de[129.69.193.26] said: 550 5.1.10 RESOLVER.ADR.RecipientNotFound; Recipient not found by SMTP address lookup (in reply to RCPT TO command) (in reply to RCPT TO command) <fs-wiwi(a)uni.passau.de&gt;: Host or domain name not found. Name service error for name=uni.passau.de type=AAAA: Host not found <fachschaft8(a)uni-wuppertal.de&gt;: host mail1.uni-wuppertal.de[132.195.64.21] said: 550 5.1.1 <fachschaft8(a)uni-wuppertal.de&gt;: Recipient address rejected: User unknown in relay recipient table (in reply to RCPT TO command) <fachschaft_kunstgeschichte(a)yahoo.de&gt;: host mx-eu.mail.am0.yahoodns.net[188.125.72.73] said: 552 1 Requested mail action aborted, mailbox not found (in reply to end of DATA command) <muwifachschaft(a)uni-muenster.de&gt;: host udcm-wwu1.uni-muenster.de[128.176.118.7] said: 550 #5.1.0 Address rejected. (in reply to RCPT TO command) <fachschaft(a)sport.kit.edu&gt;: host scc-mailin-cs-01.scc.kit.edu[129.13.174.140] said: 550-Callout verification failed: 550-550 5.1.10 RESOLVER.ADR.RecipientNotFound; Recipient not found by SMTP 550 address lookup (in reply to RCPT TO command) <suedost.fachschaft(a)geschichte.uni-regensburg.de&gt;: host b2561.mx.srv.dfn.de[194.95.235.17] said: 550 5.1.1 <suedost.fachschaft(a)geschichte.uni-regensburg.de&gt;: Recipient address rejected: undeliverable address: host mx3.uni-regensburg.de[194.94.157.148] said: 550 5.1.1 <suedost.fachschaft(a)geschichte.uni-regensburg.de&gt;: Recipient address rejected: User unknown in virtual alias table (in reply to RCPT TO command) (in reply to RCPT TO command) <Fsv-geographie(a)mx.uni-saarland.de&gt;: host m-relay2.rz.uni-saarland.de[134.96.7.8] said: 550 5.1.1 <Fsv-geographie(a)mx.uni-saarland.de&gt;: Recipient address rejected: undeliverable address: Recipient address lookup failed (in reply to RCPT TO command) <fgmewi(a)tu-braunschweig.de&gt;: host b1991.mx.srv.dfn.de[194.95.234.151] said: 550 5.1.1 <fgmewi(a)tu-braunschweig.de&gt;: Recipient address rejected: undeliverable address: host cisco-esa5.rz.tu-bs.de[134.169.4.172] said: 550 #5.1.0 Address rejected. (in reply to RCPT TO command) (in reply to RCPT TO command)