I've got a web application with approx. 30k users and growing fast. We want to enable some functionality over email, which means assigning each user a unique email address (for security reasons). Emails sent to these unique addresses should be forwarded to a PHP script. The PHP script needs access to all parts of the email - the headers, body and any attachments. I'm not sure what the right way is to set this up. We're currently using sendmail and would prefer to stick with that (this is linux, if it matters). I've been able to get an individual email forwarding to a script, but it is not scalable (in my mind) to create 30k aliases and then a new one each time a new user signs up. I'd be much happier with some type of catch-all / RegEx-based solution that just tells the PHP script the unique email address that was the recipient, which would let us look-up the user.