You can put your email here, like the guy that just responded to the rolling chassis offer, but it is better to use a private message to the seller. That "PM" for short and I saw that on other forums for a while until I figured it out.
Click on the guy's name under the post title, and it goes to a page where on the left is says "PM: Send private message"
Under that is another festival of acronyms, but I don't know what they mean.
The guy you send the PM to gets a notification and he can read it and reply privately to you.
If you do post your email here, I would go back and delete it or the whole reply after you connect. There are robots that search the internet looking for email addresses so they can send you spam.