Leveraging off the integration with Fantastical, would it be possible to have an option to communicate calendar availability via Airmail?
Would love for a BusyCal integration as their iOS app and desktop app are among the most robust for business use.
And once the decision is made, whether "accept", "decline" or "not sure". The response will sync across all devices.
For Sunrise calendar....desktop too
Chuck Colburn commented
Also include iOS stock calendar
And also include Calendar 5