E-MailRelay
Von der Webseite des Herstellers:
E-MailRelay is a simple SMTP proxy and store-and-forward message transfer agent (MTA). When running as a proxy all e-mail messages can be passed through a user-defined program, such as a spam filter, which can drop, re-address or edit messages as they pass through. When running as a store-and-forward MTA incoming messages are stored in a local spool directory, and then forwarded to the next SMTP server on request.
E-MailRelay can also run as a POP3 server. Messages received over SMTP can be automatically dropped into several independent POP3 mailboxes.