Hello Andrei.
I had the same problem and here is how I fixed it.
1. installed the “Welcome Email Editor” plugin. https://wordpress.org/plugins/welcome-email-editor/
2. In Welcome Email Editor’s settings page I changed the “Send Email As” setting form HTML to TEXT.
3. Now it works 🙂
If you want to know more on that just check out the developer’s answer on this question: https://wordpress.org/support/topic/how-to-get-started-after-install?replies=2
