Why cannot?

from my 8 years of Java experience, I would say know servlet if fine enough, don't spend too much time on J2EE. JSP, forgot it, the current stack is RESTful style, server rendered web page is dusk tech. Recently years I am addicted to the play framework, this releases you from servlet kidnapping (same as.Ruby on Rails)

Frontend : AngularJS Backend: Play framework (Java/Scala) + MySQL + Nginx (load balancer) + Redis (cache), deploy all these pieces with docker (highly recommended) if your data model not complicated, you can also just use Redis. try use websocket for push tech. FYI, This is a general bootstrapping stack for basically everything, to have different pivoting on the stack, you need expose more business knowledge about your website.

If the benefit of using dynamic typed programming language is to less care data type, my question is why you learn to program? If you just try to make something for your idea, it's fine, but if you wanna be a professional SE, then, I am sorry for you. IMO, people use the 'fast development' as a excuse to choose dynamic programming laungage is need to programming more within a team.

Or you can just use AWS SES?