With Sitecore 9 the new forms module is introduced and available by default after installing Sitecore 9. It has a lot of potential but in my opinion lacks must have features like sending emails after a form submit.
Luckily the Sitecore community starts creating solutions for this. So this week tip is to take a look at the Sitecore 9 forms extensions module of Bart Verdonck. Download it on GitHub: https://github.com/bartverdonck/Sitecore-Forms-Extensions.