Although Apple's native email application is good, it is not as widely used as the all-powerful Gmail. It is true that if you like privacy you are looking for another type of provider. You don't have to go to Tutanota or ProtonMail, but any provider is a bit more private than the native Gmail. But it is very easy to use, integrates with other features, and has a lot of technical support and many people creating new applications. A former Apple engineer has created a new client with multi-account support and called it Mimestream.
Mimestream, that's what it's called the new application that is written entirely in Swifty designed with AppKit and SwiftUI. This achieves a clean and original appearance. Its creator, Jhaveri, says that the application is designed to be fast, lightweight, and use a minimal amount of disk space.
Use the Gmail API instead of IMAP thus managing to support more specific functions of Google mail. In this way we can have categorized inboxes, aliases and signatures that will be synchronized automatically. It also has full tag integration and search operators.
One of the best advantages of this application is the ability to have compatibility with multiple Gmail accounts. It will unify everything in a single inbox. The other Gmail options will remain in this new application. In the short term, its creator intends to add new functions that make the application much more practical and useful, such as: compatibility with Google Drive; G-Suite directory autocomplete and server-side filter settings.
Jhaveri says that Mimestream only makes direct connections to Gmail and does not use intermediary servers, and adds that the application does not collect or sell users' emails. It's free while in beta. It will end up being paid and will be distributed through the Mac App Store, being compatible with macOS Catalina or later.