Hi,
I got an Exchange 2013 DAG in co-existence with a Exchange 2010 DAG, SiteAExch13A works fine, but whenever the DAG fails over to SiteBExch13B internal email flow from Exchange 2010 users to 2013 users fail to deliver. All other email flow is fine.
Telnet to SiteBExch13B doesn't work, telnet to SiteAExch13A works fine. To 13B is just goes back to the command prompt after a while, no error.
If the DAG is active on 13B, 2010 to 2013 email flow stops with:
451 4.4.0 Primary target IP address responded with: "421 4.4.2 Connection dropped due to SocketError." Attempted to failover to alternate host, but that did not succeed. Either there are no alternate hosts, or delivery failed to all alternate hosts.
- All receive connectors settings are identical between 13A and 13B
- Telnet works fine to 13A
- Telnet to 13B over WAN or LAN makes no difference
- Telnet on 13B to localhost works fine
- We have no firewalls internally on the domain
- The network adapter order is fine
- Network settings are identical between 13A and 13B
- Ping and RDP to 13B works fine.
- Antivirus (SCEP 2012) is handled by policies, so exact same settings on 13A and 13B
- Test-Mailflow (without parameters) work fine on 13B if its the active DAG server.
Thanks, any advise highly appreciated.