This is an SMTP protocol error log for virtual server ID number, connection #number. The remote host “%3”, responded to the SMTP command “text” with “error message”. The full command sent was “text”. This will probably cause the connection to fail.

This event is logged when the Exchange server sends an SMTP command to a remote server and receives a response that is not valid. The virtual server ID indicates which SMTP virtual server issued the command. The remote host indicates the fully qualified domain name of the remote server that responded to the command. The actual command issued, and the response received, are also mentioned in the event.

Possible causes for this event include faulty network card drivers and network cards that are configured incorrectly.

Note   You will see Event 7004 only if you turn up diagnostic logging on the MSExchangeTransport event source to Medium or higher.

To resolve this error, try one or more of the following:

• Make sure that the latest network card drivers and firmware are installed.
• Run any network diagnostics software that was supplied with the network cards to verify that the network cards are functioning correctly.
• If the network cards are configured to automatically detect the speed of the connected network, change the configuration to use a specific speed setting.

For additional information that may help you resolve this problem, see Microsoft Knowledge Base article 153119, XFOR: Telnet to Port 25 to Test SMTP Communication.