Dear Support team, Exchange 2010 SP2 , 3 servers in same forest, i have issue with internal emails staying in Q for 15 min before sent to server B or C, no issue with DNS servers or AD, in Q viewer i can see this error will be glad to get some help. SMTP Relay to Remote Active directory Site - 451.4.4.0 DNS query failed SMTPSEND.DNS NonExsistenDomain. thanks

Hi, Please try to use NSlookup. set q=mx domain name set q=Exchangeserver(mailservername) Please try enable protocol logging on Send Connectors, use the following command: Set-SendConnector "SendConnector_Name" -ProtocolLoggingLevel verbose Send Connector logs are located in: \Program Files\Exchange Server\v14\TransportRoles\Logs\ProtocolLog\SmtpSend. Besides, please try to run ExBPA and then post the log tab information here. Xiu Zhang TechNet Community Support