The load mitigation and anti-spam solution in Postfix is highly sophisticated thanks to Postscreen. We examine its innards and look at how to deploy it to your advantages. In previous versions of the Mail Server only one connection could be processed by each SMTP system process before moving on to the next one in the queue. That’s far from ideal when you’re processing tens if not hundreds of thousands of e-mails every day I’m sure that you will agree. For superior efficiency a single postscreen process can handle multiple connections simultaneously and act as filter, deciding which e-mail is valid and which might be sent from Spambots, before passing the job onto an SMTP process.