Not the OP, but I have a similar setup, however instead of Postfix I am using OpenSMTPd, which I found much easier to configure. Checking for false positives i

Not the OP, but I have a similar setup, however instead of Postfix I am using OpenSMTPd, which I found much easier to configure. Checking for false positives is a manual process. I've never had legitimate mail marked as spam though, only the other way round. My experience with Gmail's filter is not as nice btw. At work, I had a couple of situations where important mails from a customer were flagged as Spam, which went unnoticed for two weeks.