Hmm... This actually sounds like the job of 2 components working side by side. On the one hand, to have the BugTraq email ready for the web as soon as you receive it you need to have something kick off as soon as an email comes in and route the mail to some text file. Then you would need a script (likely the PHP component) that would grab the file from the previous component and put it up on the web. While I suppose it's possible that PHP could handle both aspects, I usually see ProcMail or some other mail handler (sometimes Perl) working the mail aspect. In that scenario, here's the route that the data should take:

Bugtraq -- sends email to your address --> ProcMail -- ProcMail routes the email to some text file --> PHP -- PHP grabs the file, finds the most recent entry and formats it for the browser --> Browser.

PHP could theoretically handle all the aspects of this process, but you would have to write a fairly hefty regular expression to parse only the BugTraq email out of your inbox. ProcMail is much better suited for this job, and is much easier to setup. Let me know if you need any help with ProcMail...I love it.