I’m always frustrated when I leave certain emails as ‘unread’ in a shared mail account, that Mailspring keeps the systray icon highlighted (in my case, blue). Opening the app to see if there is new mail is aggravating, and keeps triggering my OCD when I see this blue icon. Closing Mailspring clears the blue from the icon, but it turns blue again moments later (presumably when it checks and sees unread emails).
Track state of unread emails somehow on closing/minimizing the app. Only when the ‘count’ of unread emails changes upward, mark the systray icon as ‘new mail’. This obviously should be a preference that people can turn on/off.