How to fix email stuck in Exchange 2007/2010 queue

It’s really annoying when someone says he/she didn’t get your any email!! Which had already sent it yesterday? It means they are lying…Right? 

Nope!!! Actually there is a problem with your Exchange server that’s why it is not delivering any email to the corresponding user. Of-course it may confuse any user for a while, but this is an error known as Email Stuck which may occur in any Microsoft Exchange Server environment. 

It is one of the most irritating issues on Microsoft Outlook/Microsoft Exchange Server which stuck the emails in remote delivery queue going to any other Exchange server. You can easily look these stuck emails by opening 'Queue Viewer' tool from the 'Toolbox' on Exchange Management Console. You can notice following error code in 'Last Error' field as-

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.

So today, we’ll try to troubleshoot email stuck problem which usually occurs on Microsoft Exchange Server 2007 and 2010. But before we start, it would be better if we know the causes why we got this problem and why any email didn’t deliver to receiver. Let’s check it-

Common causes of email stuck in Exchange Server

The primary reason of occurring email stuck in Exchange server is that your Exchange server couldn’t authenticate with remote Exchange server. It is required for Exchange server to authenticate for routing email between them. Sender server tries to use X-EXPS command for authentication, but this failure occurs when firewall stops the authentication or remote server doesn’t enable X-EXPS command.

So fix email stuck issue, make sure that Exchange authentication is enabled for all receive connectors. Also check if any firewall is located between two servers, the Extended SMTP verbs X-ANONYMOUSTLS, GSSAPI, and X-EXPS must be able to pass.

So, if you checked all above basic setting, follow some given steps fix this problem in Microsoft Exchange server 2010 and 2007. 

For Microsoft Exchange Server 2010 or Exchange Server 2010 remote servers

Ø  Open Exchange Management Console. To open Exchange Management Console, make sure PC has administrative privilege. Now go to Start -> All Programs -> Expand Microsoft Exchange Server 2007 or Microsoft Exchange Server 2010, depending on which version of Exchange server you are using on your system. Click Exchange Management Console from the utility list.

The Exchange Management Console box will launch quickly. You can see there several tools including 'Toolbox', 'Organization Configuration', 'Recipient Configuration' and 'Server Configuration'.

Ø  Now click on 'Server Configuration' to expand tab, and click 'Hub Transport'.

Ø  Click on 'receive connector' tab, and find the remote Exchange server receive connector that the email is trying to be sent. You can also review stuck emails in 'send protocol logs' from Exchange server.

Ø  Now click on 'Properties' by right click on 'receive connector'.

Ø  Now verify 'Exchange Server authentication' is checked on the 'Authentication' tab.

That’s it, all setting has been done. By implement these setting your all pending email message will automatically deliver to the corresponding users.

Now send a test email to other receiver to verify that your emails are delivering to corresponding address.