3.215.192.160
ec2-3-215-192-160.compute-1.amazonaws.com
3.226.168.252
ec2-3-226-168-252.compute-1.amazonaws.com
35.172.67.220
ec2-35-172-67-220.compute-1.amazonaws.com

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