in reply to Email System Scalabilty

  1. Buy/host your own server or talk to your service provider as using catch-all addresses will like not work anyway. You need control over the mailboxes.
  2. I'm not sure what you're aiming at, but if you want to let different users see different mails, give them separate mailboxes.
  3. This does not work. One man's spam is another's important newsletter. I suggest you look at what MailChannel, MessageLabs, POBox and the other mail filter providers do.
  4. GeoIP by MaxMind is also available with commercial support. Reporting spam back to the server is likely futile unless you block early in the SMTP phase, and from your vague description it sounds like you want to implement your solution much later.

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