The IInetLogInformation::GetBytesSent method retrieves the number of bytes sent by the server to the client.
virtual DWORD STDMETHODCALLTYPE GetBytesSent( VOID );
Logging modules should query for this method if a server instance has set the MD_EXTLOG_BYTES_SENT flag of the MD_LOGEXT_FIELD_MASK metabase identifier.
LogExtFileBytesSent, MD_LOGEXT_FIELD_MASK