34.193.143.145
ec2-34-193-143-145.compute-1.amazonaws.com
52.4.54.64
ec2-52-4-54-64.compute-1.amazonaws.com
52.72.251.15
ec2-52-72-251-15.compute-1.amazonaws.com
54.204.101.212
ec2-54-204-101-212.compute-1.amazonaws.com

us-smtp-inbound-1.mimecast.com.
us-smtp-inbound-2.mimecast.com.