We are experiencing a problem emailing from one exchange server to another. Our server is an SBS2008 with exchange 2007 atc.local on vlan 1 192.168.0.x the other server is an sbs2011 with exchange 2010 speedy.local on vlan 16 192.168.16.0. For a short time we were able to email between both servers after i created an entry in the hosts record, i.e.
192.168.16.253 mail.speedy.com on the sbs2008
192.168.0.2 mail.atc.com on sbs2011
over the last week this has stopped working when emailing from sbs2008 act.local to sbs2011 speedy.local, we receive an NDR back that says 550 4.4.7 QUEUE.Expired; message expired ##
When i look at EMC/toolbox/que viewer I see this DnsConnectorDelivery Retry 1 Thursday, June 27, 2013 9:25:45 PM 451 4.4.0 Primary target IP address responded with: "421 4.3.2 Service not available." Attempted failover to alternate host, but that did not succeed. Either there are no alternate hosts, or delivery failed to all alternate hosts.
when i go to a command line and ping mail.speedy.com it resolves to the internal address and i get a reply.