To avoid confusion and/or misconceptions, let me state right now: I know that what I need to do is not SMTP-compliant, and in my opinion courier-esmtpd is doing the perfectly right thing here. (mostly because I'm a big courier-fanboy, using it since ca 8 years :)

Ok, here's my problem: I've setup courier in a closed network (i.e. no connection to the Internet whatsoever), as a replacement for a quite old postfix/cyrus setup. Within this network, there are many programs/scripts which need to send mail to users, and do this using SMTP. Problem: Those programs usually send RCPT TO:<username> instead of RCPT TO:<username[at]domain> (the former results in "513 Syntax error")

I'm fully aware that RFC2821 requires the latter syntax (apart from mails to <postmaster>), but I need to cope with those erroneous programs/scripts -- there are too many of them, written by too many people, to just go and fix them.

So: Any hints how to do this? I wasn't able to find any config-option for this, and I don't exactly feel like hacking around in the source...

tia,