I have to look into the logs and see details. One thing we can do quickly is to add RBLs (Realtime Blackhole list). There are few sites who maintain the RBLs and we can just configure our server to use that RBLs. And our mail server will automatically reject whatever the traffic comes from domains and IPs listed on RBL.
I am systems administrator with over 11 years of experience managing server infrastructures and data-center operations across multiple platforms (mostly Microsoft, partially Linux) mostly in virtualized environment (both Hyper-V and VMWARE). Effectively plan, install, configure and optimize the IT infrastructure to consistently achieve high availability and performance.
I will be glad to help you.
Skills: -
• Extensive experience in installation, administration and networking in various environments.
• Highly skilled at vSphere 6 deployment, including managing ESXI hosts and VMs, Storage (iSCSI or vSAN), Networks (Standard or Distributed Switches), configuring vMotion, Fault Tolerance, High Availability.
• Highly skilled at Microsoft Server platform (starting from Windows 2000 up to 2012) Administration including configuration of Active Directory, DNS, IIS, DHCP, System Center 2012, Load Balancing, Failover Cluster, Quorum etc.
• Experience in Virtualization (both Hyper-V and VMWARE).
• Sharepoint Administration (expertise in Sharepoint Designer).
• Familiar with configuration of network devices (like Cisco PIX Firewall, DFL-800 Dlink firewall,