I have installed a single 2013 CAS server and a single 2013 MB server in my testlab. I already have a 2010 cas server, Hub Server, and mb server in the testlab. After installing 2013, and redirecting my mail to the 2013 CAS server, mail is flowing to the 2013 MB server. In the Queue Viewer for the 2013 DB server, I see the message with the next hop being SITE:mysite; Version:14, Delivery Type is SMTP Relay to Mailbox Delivery Group; Status is Retry;

Error:

"Wednesday, June 19, 2013 12:11:19 PM" "[{LRT=6/19/2013 12:10:19 PM};{LED=451 4.4.0 Primary target IP address responded with: ""451 5.7.3 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. The last endpoint attempted was (IP of 2010 Hub:25};{FQDN=2010 Hub Server FQDN};{IP=2010 Hub Server}]"
Submission Undefined Ready 0  

I am at a loss on how to correct this. Is there a jedi master out there that can help?

I just got it to work!!!

I had to create a new receive connector on the  2010 hub server. I currently have authentication to Basic Authentication, and exchange server authentication and all is well. Thanks for those who already began investigating.

• Marked as answer by spidey24 Wednesday, June 19, 2013 6:44 PM

Ah, thank you so much.  This issue was dragging!!!!!!!!!

So annoying, such a simple fix but feel like the troubleshooting tools on 2013 aren't great.  However they maybe just more command line based now and I'm more of a lazy GUI man :-/

Thanks again...on with the migration.

I know it has been a year since this thread, but I wanted to say thank you. This worked for me after many hours of troubleshooting. I thought just checking Anonymous users under the Permission Groups would work. But that isn't the case, I needed to add "Exchange Server authentication" under the Authentication tab. I was able to telnet fine with the anonymous users, hence my hours of troubleshooting. Your post did it so THANK YOU!