If you use Gmail, it has been a long time since there has been a legitimate non-browser based client specifically for the service. Apple Mail and others can get the job done, but none have all of the expected Gmail features integrated.
Mimestream, in open beta, looks to fill that gap. Thanks to Six Colors for surfacing this for me.
As a native app written in Swift, Mimestream leverages the full power of macOS to deliver a lightning-fast and instantly familiar experience. Instead of using the IMAP protocol, Mimestream utilizes the Gmail API to enable an enhanced set of features that let you work with ease.
For my personal email, I’ve moved to iCloud as I’m able to get all of the features I like (2 TB storage, custom domain, privacy) with my Apple One plan. But I still have to use Gmail for work.