Other email clients such as AirMail are recognised by MacOS as an email client, which enables some it highly efficiency-impacting benefits, such as:
• set Missive as default email app
• make the emails searchable through Apple's Spotlight and readable by Siri.
• have MacOS and iOS recognise dates and times, make them clickable, which creates a calendar event when clicked on, containing a link in the URL field that links back to the corresponding message.