I set up an exchange server on Mail. A few months ago, if I used the SEND later option, it would send an email at any time. Suddenly this option stopped working. I called up Apple Customer Support, and they informed me this function never worked in this manner. They said, "The computer had to be on. If I wanted to send it later." That doesn't sound right to me. Why give the option of sending emails later if you have to have the computer on at all times!?
That's the whole point of using the “send later” feature, so you can take it off your mind.
For example, Gmail also has this feature, and it works perfectly. You don't have your device turned on.
The annoying thing about macOS Email is, that even if you open your computer, if it's later than the planned time, it won't send the email anymore. You need to do it manually. In this case, you can also save the email as a draft and send it later. Quite useless for now.
No computer will do anything unless it's powered up. Do you really want a computer that continues to work when the power is shut off? That doesn't even make sense to say out loud.
Send later in Mail not working
