You can use Hiver’s Shared Labels and Shared Contacts features no matter what email client you’re using. The shared labels would show up like any other Gmail labels show up on your email client. And your shared contact groups would work like any other contact group.
However, Hiver’s other features like email notes, templates etc. are currently not supported on desktop and mobile email clients. We’re working on building support for the most popular email clients, and you can write to us on firstname.lastname@example.org if you want to know more about this.