How can I see real time smtp logs on Exchange 2010

SMTP logging is diabled by default. You can read about it and how to enable it at these links.

Understanding Protocol Logging: http://technet.microsoft.com/en-us/library/aa997624.aspx

Configuring Protocol Logging: http://technet.microsoft.com/en-us/library/bb124531.aspx

 

Set-ReceiveConnector "My Receive Connector Name" -ProtocolLoggingLevel Verbose

Set-SendConnector "My Send Connector Name" -ProtocolLoggingLevel Verbose

And could see the logs on

C:\Program Files\Microsoft\Exchange Server\V14\TransportRoles\Logs\ProtocolLog