I had a post on here yesterday regarding this problm (can't find it through all the ones here lol). I got the problems sorted but I have one more (and i'm also getting this on another machine that I built with qmail.
The error i'm getting in /var/log/qmail/smtp/current is:
tcpserver: fatal: unable to figure out port number for -x
Not sure exactly where i've gone wrong but it's strange that it's on both machines.