Programatically add new subscriber

Hello guys, I’m using a Contact Form 7 to get the name and email from my visitors and send me their messages. I’d like to automatically subscribe the visitors to my e-Newsletter list but there is no native integration between Contact Form 7 and e-Newsletter plugin. I’m wondering if I could extend Contact Form 7 to add the users to my subscribers list. What would be your advice for this scenario? Thanks!