wip/smtp.proxy 1.3.3 NetBSD

smtp.proxy is an application level gateway for SMTP. It connects a client to a server running on another machine watching that the protocol is accomplished. If commands outside the specification are sent, they are not forwarded to the server. Additionaly smtp.proxy offers a small email address control (only email with a certain sender or recipient address can pass through) and can optionally remove the `Received:' lines from the mail header. Instead of forwarding the connection to a remote server, smtp.proxy can feed it into a local mail server, e.g. sendmail.