3.230.255.188
ec2-3-230-255-188.compute-1.amazonaws.com
52.0.172.242
ec2-52-0-172-242.compute-1.amazonaws.com
54.175.196.40
ec2-54-175-196-40.compute-1.amazonaws.com

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