A lot of people on some of my subscriber lists use the Out of Office auto response feature of their email client when they are on holiday or out of the office (strangely enough!).
By putting a valid email address as the From and Reply-To addresses means that a lot of useless messages come pouring in when a campaign is sent.
One solution would be to use a no-reply type address. Alternatively a rule could be set up in the email client to divert such messages to a temporary folder or the trash folder. Another would be to just put up with it.
What do other people do and what is CM's expert advice?
Like you already pointed out, there's several ways to go about this.
In most cases, I think I would set up a separate address to send the campaign from (email@example.com), which I would only access through IMAP or webmail, and set up some filters to separate out the Out of Office replies, etc.
In my experience, campaigns tend to get a few replies with unsubscribe-requests, and also replies to the newsletter contents. Having a real address that subscribers can reply to, and that is read, is a good thing, IMO. However, I like to keep it separate from other email.
I'd agree with Stig - having a reply address that your subscribers can actually use is too valuable to just shut off because of inconvenient messages.
Better to have an email address that is separated, and filter it with some rules.