We have a strange problem, we have set up a new Lotus Protector cluster with one cluster manager and two cluster nodes. The manager and one of the nodes are on the same subnet, the second node is on another subnet with another ISP, VPN tunnel is established between the subnets. All nodes is configured with private ip addresses and SMTP traffic is NATed in. It’s only the cluster nodes that send and receive email. When we receive email from some domains, it arrives first at mx01 (Pri 10), then, precise 61 seconds later it arrives at mx02 (Pri 20). Depending on the retry policy of the sender, it then arrives with the same interval (61 sec) every time the sender’s mail server retries. The strange is that we receives and deliver the email to the end user every time, so they got a lot of the same email.
It looks like the sending mail server don't "see" that the message is delivered, and put it in the retry queue.
Has anybody else encountered this problem before?
Any help or suggestion is welcome.