We have just started to see outgoing to the internet messages getting queued up. Every thing was fine until 2 days ago. Incoming and internal mail is ok. We get the following error in the queue viewer on the Ex2k10 box
451 4.4.0 Primary target IP address responded with “421 4.2.1 Unable to connect. “Attempted to failover to alternate host, but that did not succeed. Either there are no alternate hosts, or delivery failed to all altenate host.