I believe "noreply" is bad customer service
stevetbutler.blogspot.co.uk
stevetbutler.blogspot.co.uk
I have seen a good compromise for this, though: a piece of software I use sets the sending address to "noreply.support@mydomain.com"; if you want to reply to the message (and you aren't a spammer or mailer-daemon), you simply delete the "noreply." from the beginning.
Of course there is always the problem of spamming but there are plenty of third party filtering services which I'm sure could help with that.
It's unfortunate that auto-generated spam and so on has become such a problem because the flexibility and freedom of the e-mail protocol is why it's stood the test of time as a communication platform between companies.