The original message was received at Tue, 28 Jan 2025 09:08:55 +0100 from [165.154.252.200] ----- The following addresses had permanent fatal errors ----- (reason: 550 5.5.1 Open relay is not allowed) (reason: 550 5.5.1 Open relay is not allowed) ----- Transcript of session follows ----- ... while talking to mail.mfa.gov.cn.: >>> DATA ... User unknown >> DATA ... User unknown ... Host unknown (Name server: .: host not found)