The last thing guys who bulk register+park domain typos, TM squats, etc. want is human contact.
I know that, nut there are ways to solve the problem without losing sales.
It's not rocket science, the email address can easily be nothing more than an auto-responder with a link to a site where you can bid on the domain in question. No human contact or spam for that matter, only valid bids that have been verified to be a human posting them.
Like I said, the guy only needed a valid contact a year ago, or even a form to "buy this site", and I was willing to pay a decent price for what I wanted but his 'business model' didn't allow for it and it ended up giving it away in the end.
Money left on the table.
I'm sure there are ways, like I described above, that people with 10s of thousands of domains can at least make it available to pay off without making it difficult to deal with by people on either side of the coin.
FWIW, the sites that have a minimum bid of $1K always crack me up because many of those domains are worth hundreds, not thousands, but their failing business models aren't allowing them to cash in.