Mimestream 1.4.1 for Mac can be downloaded from our website for free. The actual developer of this software for Mac is Mimestream, LLC. The application belongs to Communication Tools.
From the developer:
Mimestream is a native macOS e-mail client for Gmail. The application combines your favorite Gmail features with the power of a native macOS app so you can move through your e-mail effortlessly. Instead of using the IMAP protocol, Mimestream uses the Gmail API to enable an enhanced set of features that let you work with ease.
Your data and credentials are stored only on your device, and the app only makes direct connections to Gmail.
You may want to check out more Mac applications, such as SerialMailer, Mail Archiver X or MailMate, which might be related to Mimestream.