The original message was received at Tue, 28 Jan 2025 09:33:32 +0100 from [165.154.252.200] ----- The following addresses had permanent fatal errors ----- (reason: 550 Host unknown) ----- Transcript of session follows ----- 451 4.4.1 reply: read error from b5e584ac541a4754af8f59bf2915a9a7.pacloudflare.com. ... Deferred: Connection reset by b5e584ac541a4754af8f59bf2915a9a7.pacloudflare.com. ... Deferred: Connection timed out with fri.com.cn. ... Deferred: Connection timed out with frigrite.com.cn. ... Deferred: Connection refused by grip.net.cn. ... Deferred: Connection timed out with mail.sg.mne.gov.pt. ... while talking to nottingham-edu-cn.mail.protection.outlook.com.: >>> DATA ... Deferred: 451 4.7.500 Server busy. Please try again later from [83.138.65.30]. (AS780082) [HK3PEPF0000021D.apcprd03.prod.outlook.com 2025-01-29T04:01:51.813Z 08DD3E6A91D87254] 550 5.1.2 ... Host unknown (Name server: standens.cn: host not found) Warning: message still undelivered after 4 hours Will keep trying until message is 1 day old