Hello, I’m member of IT Team , an Korean Company.
I’m writing you because we have some problems with email delivery to some domains managed by messaglabs.com service provider.
Our investigation results is that:
the servers below, linked to sc.com domains are dropping connection to our smtp servers
○ sender IP : 61.38.250.111, 61.38.250.112, 61.38.250.150
○ logs
Thread-74[SC.COM] (gateway.DnsJavaManager.getConnection:465) [DNS] SC.COM's MX Entry : cluster4.us.messagelabs.com. A Records[ 0] / IP : 67.219.250.203 2019-12-02 14:02:11
Thread-74[SC.COM] (gateway.DnsJavaManager.getConnection:465) [DNS] SC.COM's MX Entry : cluster4.us.messagelabs.com. A Records[ 1] / IP : 67.219.246.97 2019-12-02 14:02:11
Thread-74[SC.COM] (gateway.DnsJavaManager.getConnection:465) [DNS] SC.COM's MX Entry : cluster4.us.messagelabs.com. A Records[ 2] / IP : 67.219.250.193 2019-12-02 14:02:11
Thread-74[SC.COM] (gateway.DnsJavaManager.getConnection:465) [DNS] SC.COM's MX Entry : cluster4.us.messagelabs.com. A Records[ 3] / IP : 67.219.250.107 2019-12-02 14:02:11
Thread-74[SC.COM] (gateway.DnsJavaManager.getConnection:465) [DNS] SC.COM's MX Entry : cluster4.us.messagelabs.com. A Records[ 4] / IP : 67.219.246.193 2019-12-02 14:02:11
Thread-74[SC.COM] (gateway.DnsJavaManager.getConnection:465) [DNS] SC.COM's MX Entry : cluster4.us.messagelabs.com. A Records[ 5] / IP : 67.219.251.49 2019-12-02 14:02:11
Thread-74[SC.COM] (gateway.DnsJavaManager.getConnection:465) [DNS] SC.COM's MX Entry : cluster4.us.messagelabs.com. A Records[ 6] / IP : 67.219.251.59 2019-12-02 14:02:11
Thread-74[SC.COM] (gateway.DnsJavaManager.getConnection:465) [DNS] SC.COM's MX Entry : cluster4.us.messagelabs.com. A Records[ 7] / IP : 67.219.250.97 2019-12-02 14:02:11
Thread-74[SC.COM] (gateway.DnsJavaManager.getConnection:465) [DNS] SC.COM's MX Entry : cluster4.us.messagelabs.com. A Records[ 8] / IP : 67.219.246.107 2019-12-02 14:02:11
Thread-74[SC.COM] (gateway.DnsJavaManager.getConnection:465) [DNS] SC.COM's MX Entry : cluster4.us.messagelabs.com. A Records[ 9] / IP : 67.219.246.203 2019-12-02 14:03:11
Thread-74[SC.COM] (gateway.DnsJavaManager.getSMTPSessionInfo:598) [DNS] 602 connect to 67.219.246.203 connect timed out 2019-12-02 14:03:11
Thread-74[SC.COM] (gateway.DnsJavaManager.getConnection:465) [DNS] SC.COM's MX Entry : cluster4a.us.messagelabs.com. A Records [0] / IP : 3.222.201.247 2019-12-02 14:03:11
Thread-74[SC.COM] (gateway.DnsJavaManager.getConnection:465) [DNS] SC.COM's MX Entry : cluster4a.us.messagelabs.com. A Records [1] / IP : 52.73.243.182 2019-12-02 14:03:11
Thread-74[SC.COM] (gateway.DnsJavaManager.getConnection:465) [DNS] SC.COM's MX Entry : cluster4a.us.messagelabs.com. A Records [2] / IP : 34.237.164.170 2019-12-02 14:04:11
Thread-74[SC.COM] (gateway.DnsJavaManager.getSMTPSessionInfo:598) [DNS] 602 connect to 34.237.164.170 connect timed out 2019-12-02 14:04:11