Email between users (members)?

I am new to drupal and managed to create a simple site. However, I would like to have a way for members to email each other via an email form on the website (ideally where comment forms are located underneath articles).

For example, say member A made an article called "a" and then member B sees article "a". Is there a module/way for member B to send a quick email to member A with a simple button below article "a"?

Thanks