parallels has a workaround for the error "qmail-queue-handlers: Unable to get 'From:' string from SMTP session"
under this post: http://forum.parallels.com/showpost.php?p=400963&postcount=51
but I'm not sure if thats the best solution. After my investigation this error only shows up when the rDNS of the sender is empty or the from sender is empty.
Till now this is only showing up on spammers. No sender is OK. According to RFC 821, it is legal to deliver messages with no sender address.
But no rDNS is typical for spammers. So to me, the spam is causing most of the "unable to get from" errors which are causing the "pipe" errors.
first I will block all connections from servers that have no rDNS entry via spamdyke.
I think this will downsize the errors. I only have a few but I'm interested of how few will be left.
Note that it might be different on other servers. I'm using qmail (of course),qmail-scasnner,spamdyke and have submissions port enabled.
It could be different with other combinations.
Interested what you guys think about it.