@vernon yes that is correct. Hosting in Webflow is totally separate than the email service on a domain. I think this is a good move from Webflow since Webflow is absolutely not a company that is involved in the email game.
In my opinion, clients should never use the email services of the big hosting providers (hostgator, bluehost, dreamhost, godaddy, etc) as they are generally a horrible user experience with very poor support.
If you think about it, in today’s world most clients will be used to either Gmail or Outlook in a professional setting. These are products backed by the biggest companies in the world - and their job is to do one thing REALLY well (email).
At the end of the day the cost of Gmail for business (always my recommendation to clients), $5 per email address per month, is a great deal as it also gives you access to the entire suite of Google professional tools (Drive, hangouts, etc).
When I have clients ask me about this, I always make sure to lay out the clear distinction between hosting & email, and also explain the above points about why it can be good to separate the two instead of paying for 1 cheap “bundle”.
Hope this helps!