Handling public IP


I’ve made some research but couldn’t find an answer to my question. I want to use Docker Swarm to handle containers containing postfix + dkim that send mails (obviously) but I want those containers to have public IPs and for instance if a node from a cluster goes down, containers migrate to an other node, keeping their original IPs and can go on sending mails. Is this possible ? For information, i’d like to do this on a 30 servers cluster and I have public IPs with different ranges and netmasks.

Thanks in advance

perhaps of interest: https://docs.docker.com/engine/swarm/ingress/#publish-a-port-for-a-service