Whether it's gmail, hotmail or any other free email service really doesn't matter. The scammers know where all the free email services are and quickly switch from one to the other. Both those ads are obvious frauds, partly because of the price, but also because they want you to use their private email rather than use the craigslist generated email at the top. Always flag these ads when you see them, I do. If you are at all reluctant to flag the ad, try getting your own separate email address on gmail, and use it to respond to them, and ask where you can see the tractor. If they say you can't see it cause it's in another city ready to ship, you know it's a scam and flag every ad that uses those photos and that email address.
That is, if you want to play Wyatt Earp.