Customers being comfortable with email doesn't mean your backend has to use email too. The most practical approach is: keep the front-end communication in the way customers prefer, but centralize all incoming inquiries, quotations, and POs in one system on the backend. Customers won't notice any change on their end, but your data becomes structured, versioned, and trackable. Going further, you can give willing customers a product page where they can browse specs and pricing themselves—customers who want to use it will save you a lot of back-and-forth explanation time, while those who prefer email can keep using it, but your side still captures orders into the system neatly. Change doesn't require forcing everyone to switch all at once. Get your own workflow running smoothly first, then gradually guide customer habits. Your customer-facing approach can adapt gradually.