Maintain log files in stateserver

Hi

I want to develop for log file in webserver.we are having dedicated server.we are sending new letter for every user that we having.i want to know how opens and clicks that Newsletters.

right now we are maintaining pixel that redirect to our page then we Add those infromation in XML file.there is problem in XML file we are getting Problem To Load Data at certain time that come to 6 MB.

i want to maintain that information in log file.Let me know if Any one Can Help me On this issue.

Give me Right direction for this issue.

That Help full for me..

Thanks

I found nice Example we can log in IIS server.there we read pixel data..that users log our site..