I’ve been thinking about spam. One of the problems I have is the Taiwanese spammers who send me crap with no To: line, forged sender, etc. I use Outlook Express – not Outlook, and I can’t hear you booing – for email, and because of the munged headers there’s no way I can set up an OE rule to do The Right Thing. What I need is a mail-filtering solution with the following characteristics:

  • It must work with any mail program, on any platform, which pretty much means it must be a POP3/IMAP server.
  • It must be capable of preserving mail-account information so that the user’s mail program can still use the correct account to send replies. This means that the server functionality must support multiple POP3/IMAP mailboxes.
  • It must run entirely on the user’s own machine.

The obvious solution would be procmail, but that seems to fall just short of the second requirement and it doesn’t actually fetch mail itself (it relies on being invoked by the MTA for that) so using it would involve the extra headache of compiling and setting up another program for that purpose – in my case on Windows, which is not usually the primary platform for such things. Fetchmail has the opposite problem: it fetches but doesn’t serve. What I really need is an N-in N-out POP3/IMAP proxy (both client and server) with built-in filtering. Does anyone know of one, especially one that already runs on Windows? If so, please let me know. Otherwise, I might whip one together myself.