i've problem with sending mail from exchange 2010 (NLB and DAG) to Exchange 2007 (legacy) on same domain, same forest and same organization.
i've error that sound
"4188.8.131.52 Primary target IP address responded with: "4184.108.40.206 cannot achieve Exchange Server authentication. " Attempted failover to alternate host, but that did not succeed, either there are no alternate hosts, or delivery failed to all alternate hosts"
i've create receive connector on both exchange server 2010 and 2007 with authentication "exchange server" and Permission "legacy exchange Server, Exchange Server"
But still no luck ,
does anyone can help me please