Typically, noreply addresses are used as a blackhole for mail that probably won't be replied to, and any replies are either auto-generated (e.g. mail delivery failure notices), spam, or other undesirable mail.

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.

That sounds like a good idea. In general I think for companies who are fairly substantial in size and have people who would otherwise respond to e-mails sent to the relevant department, having a form of "e-mail switchboard" seems like a vast improvement in customer service.

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.

Apologies if this doesn't belong here, I thought the community might find it an interesting topic of discussion though.