We just replaced a failed SBS 2003 Server with Exchange 2010. It is running on a XenServer Virtual machine under Server 2008 R2. No changes were made to the network. I'm getting mail stuck in the queue returning various versions of error 4.4.2 Some say the connection dropped due to a socketerror, others indicate the timeout was exceeded. When I restart the box most of the queued mail is sent. I've seen various discussions of similiar issues with no clear explanation that I understand. to summarize: Exchange 2010 - New install No Network Changes Sunbelt VIpre Enterprise Virus Protection Most mail flows but some sticks in the queue with various forms of 4.2.2 errors We are not in any black lists When the exchange server is restarted most of the messages are sent. Any suggestions would be appreciated Kevin COnde

The first thing to do is remove any third party software. After doing so, reboot the machine. Blacklists wouldn't give those kinds of errors. Ensure that your router isn't scanning SMTP traffic. Simon.Simon Butler, Exchange MVP Blog | Exchange Resources

Hi, Could you post the whole error message here? Additionally, any error message appears in the Event Log? And turn on the Protocol Logging on the Send Connector, check it Thanks AllenAllen Song