Logs accesible via web

[Andr�s]

Hello.

Now that I have my server more finished I would like to know what do I have
to use to log how many e-mails my system sends, receives, which user uses
more the e-mails...

What program do I have to use for this?
Is it possible to access all this information through a web interface (as
for logs from http servers, ftp servers, news servers...)?

Thanks.