3.93.255.74
ec2-3-93-255-74.compute-1.amazonaws.com
44.199.17.66
ec2-44-199-17-66.compute-1.amazonaws.com
52.45.231.139
ec2-52-45-231-139.compute-1.amazonaws.com

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