The flip side of that coin is specialization. Many operators believe that hosted email services are useful mainly to companies interested only in general-purpose email use and that any specialized application requires an in-house deployment. This might be true depending on the app but it might not depending on the capabilities offered by the hosted email provider. Email marketing is a great example. Some hosted email providers have special service suites aimed specifically at email marketers, many of whom can send out thousands of emails per month, focused not so much on communication as they are on marketing. These service providers deliver more than just volume, too, as they also offer custom email creation tools and sophisticated marketing and tracking metrics.
If privacy is your number one concern, perhaps you should go with Protonmail. You can upgrade to an email with your domain easily on a web interface under “Protonmail Plus” or “Protonmail Visionary” plans. However, the plans can be rather expensive, as getting only 20 GB storage space could cost you at least €24/user/month/yearly. Most email hosting providers retain your emails for months even after you delete your account. This Swiss email provider will destroy all your data when you delete your account.
An example here is the rapidly growing trend of "inbox zero." It's actually known by a variety of names, but it refers to the practice of keeping your email inbox count at zero stored emails. Essentially, it's dealing with every email as it comes in and then deleting or archiving each one so that your inbox is always empty. This boils down to a fundamental shift in how users are utilizing their email inboxes.