I don't know about email marketing, for me, it's a little dirty, maybe because of constant scammers, spammers bombarding my email but it's really annoying. Even if it's more effective(I doubt that) I wouldn't choose that. Instead of that, Social media is a way better platform for increasing your audience on your site. However, I'm not a pro in this theme so you better ask some real agency that is working in this field for a long time. I can recommend these guys from digital marketing Liverpool, they have a lot of certified specialists that are working in this field for a long time.