The original message was received at Thu, 29 Feb 2024 09:38:53 -0500 from m0338037.ppops.net [127.0.0.1] ----- The following addresses had permanent fatal errors ----- <Sultan_Orazbayev@hks.harvard.edu> (reason: 554 5.4.14 Hop count exceeded - possible mail loop ATTR34 [CH2PEPF0000009B.namprd02.prod.outlook.com 2024-02-29T14:38:54.030Z 08DC370C9A7918C9]) ----- Transcript of session follows ----- ... while talking to hu.mail.protection.outlook.com.:

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DATA <<< 554 5.4.14 Hop count exceeded - possible mail loop ATTR34 [CH2PEPF0000009B.namprd02.prod.outlook.com 2024-02-29T14:38:54.030Z 08DC370C9A7918C9] 554 5.0.0 Service unavailable