When will Send Later be available?
We are working on it since July 2021 and it should available in September 2021.
How the send later feature is working ?
For sending at chosen date and time, the computer has to stay awake and Mail application open. The message will remain in the Outbox folder. If at the time of the scheduled message it is not possible to send it, the email will be sent as soon as possible when back online. There is no cloud service and therefore no privacy issue, all messages remain on your computer. In the future, a cloud service might be available and so it would be possible to send a message when your computer is turned off.
Which versions of Apple Mail is it compatible with?
It is compatible with Apple Mail 14 macOS Big Sur and macOS Monterey.