mailspring

Install command: 
brew install --cask mailspring

Name: Mailspring

Fork of Nylas Mail

https://getmailspring.com/

Cask JSON API: /api/cask/mailspring.json

Cask code: mailspring.rb on GitHub

Current version: 1.16.0

Requirements: macOS >= 11

Versions:

Intel tahoe 1.16.0
sequoia 1.16.0
sonoma 1.16.0
ventura 1.16.0
monterey 1.16.0
big sur 1.16.0

Analytics:

Installs (30 days)
mailspring 46
Installs (90 days)
mailspring 166
Installs (365 days)
mailspring 689