There are two ways to receive an email when there is a new post
~ the white "subscribe" button at the top (right)
~ or the check box at the bottom (right) corner
I.
When you see a "topic" which interests you or if you wish to subscribe to the whole forum, you can click the white "subscribe" button at the bottom right corner of screen (in Chrome.. ) and you will receive an email each time someone replies to that "topic".
II.
When you are posting a reply this is another way to "subscribe" to: "Email me whenever there is a new post to this topic". This is at the bottom left corner (in Chrome.. )