this is with sys=name dom=domain.dom. it works fine with sys=name.domain.dom. mxdial(/net/tcp!hotmail.com, , , mx) sending /net/dns 'hotmail.com mx' sending /net/dns 'hotmail-com.olc.protection.outlook.com ip' mx list: hotmail-com.olc.protection.outlook.com 2 mx list: hotmail-com.olc.protection.outlook.com 2 104.47.5.33 mx list: hotmail-com.olc.protection.outlook.com 2 104.47.4.33 mxdial trying hotmail-com.olc.protection.outlook.com [/net/tcp!104.47.5.33!smtp] 220 HE1EUR02FT027.mail.protection.outlook.com Microsoft ESMTP MAIL Service ready at Mon, 29 Nov 2021 18:18:17 +0000 EHLO 9ramnode.org. 501 5.5.4 Invalid domain name [HE1EUR02FT027.eop-EUR02.prod.protection.outlook.com] HELO 9ramnode.org. 501 5.5.4 Invalid domain name [HE1EUR02FT027.eop-EUR02.prod.protection.outlook.com] Mon Nov 29 18:18:18 +0000 2021 connect to /net/tcp!hotmail.com (hotmail-com.olc.protection.outlook.com:104.47.5.33) hello: 501 5.5.4 Invalid domain name [HE1EUR02FT027.eop-EUR02.prod.protection.outlook.com] QUIT 221 2.0.0 Service closing transmission channel smtp 71065: Permanent Failure : lib ;