On Fri, Sep 15, 2000 at 09:17:16PM -0400, Sam Varshavchik wrote:

AutoTURN is a concept in qmail, to emulate ETRN. An admin modifies his/her qmail, so that instead of just invoking qmail-smtpd for incomig connections, a shell script is run, which first runs qmail-smtpd, and then runs maildir2smtp, part of the serialmail package, delivering mail to the IP from where that connection came. It's a smarter way of doing ETRN, because the client doesn't actually have to send an ETRN command, and the system works with ALL smtp clients. Because the system works like the old SMTP TURN, but is automatic, Dan called it AutoTURN.

Well, seeing as courier's smtpd is also a module, like qmail-smtpd, in theory, courier could be made to do AutoTURN. One would need to patch the standard serialmail package to take account of the fact that courier writes the Delivered-To: and Return-Path: headers in the reverse order to qmail (or patch courier to copy qmail), and secondly, one would have to supply serialmail with a location for a "qmail-queue", so that it can submit the occasional bounce message, in case a client rejects a message (I suppose a qmail-queue that calls courier's submit would work). Too much work I say, but I see no other way out, because Sam has made it clear that ETRN is a no-no in courier.