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do you have the auth set the same on all servers<br />
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<a href="http://exchangeadventures.wordpress.com/2010/05/31/routing-messages-between-two-exchange-20072010-fails-with-%E2%80%9C451-5-7-3-cannot-achieve-exchange-server-authentication-attempted-failover-to-alternate-host-but-that-did-not-succeed-eithe/" rel="ugc">http://exchangeadventures.wordpress.com/2010/05/31/routing-messages-between-two-exchange-20072010-fails-with-%E2%80%9C451-5-7-3-cannot-achieve-exchange-server-authentication-attempted-failover-to-alternate-host-but-that-did-not-succeed-eithe/</a>
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do you have the auth set the same on all servers

http://exchangeadventures.wordpress.com/2010/05/31/routing-messages-between-two-exchange-20072010-fails-with-%E2%80%9C451-5-7-3-cannot-achieve-exchange-server-authentication-attempted-failover-to-alternate-host-but-that-did-not-succeed-eithe/ [http://exchangeadventures.wordpress.com/2010/05/31/routing-messages-between-two-exchange-20072010-fails-with-%E2%80%9C451-5-7-3-cannot-achieve-exchange-server-authentication-attempted-failover-to-alternate-host-but-that-did-not-succeed-eithe/]

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You sir, rock. &nbsp;Thank you, thank you, thank you!!!!!!!!!!!!!!!!!!!!!
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You sir, rock.  Thank you, thank you, thank you!!!!!!!!!!!!!!!!!!!!!

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while I'm on the same/similar subject...<br />
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Queue was only one of my problems. &nbsp;Another one of my problems was that I couldn't keep my Cluster up. &nbsp;The name cluster name kept going offline and I would have to restart the cluster service and try to bring the name back online from the other member.<br />
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Do you think it is related? &nbsp;For example, do the two exchange members communicate in a similar way?
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while I'm on the same/similar subject...

Queue was only one of my problems.  Another one of my problems was that I couldn't keep my Cluster up.  The name cluster name kept going offline and I would have to restart the cluster service and try to bring the name back online from the other member.

Do you think it is related?  For example, do the two exchange members communicate in a similar way?

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I have two exchange 2010 servers. &nbsp;One in my office and one at the datacenter, which are separate AD sites. &nbsp;My datacenter exchange is where postini delivers.<br />
<br />
I'm seeing a 451 5.7.3 cannot achieve exchange server authentication. &nbsp;Both of my Exchange servers have the default Integrated Windows Authentication checked on the CAS settings. 
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I have two exchange 2010 servers.  One in my office and one at the datacenter, which are separate AD sites.  My datacenter exchange is where postini delivers.

I'm seeing a 451 5.7.3 cannot achieve exchange server authentication.  Both of my Exchange servers have the default Integrated Windows Authentication checked on the CAS settings. 

Exchange 2010 DAG 800 mails in queue! help!

Exchange is the server side of a collaborative application product that is part of the Microsoft Server infrastructure. Exchange's major features include email, calendaring, contacts and tasks, support for mobile and web-based access to information, and support for data storage.