Local Mail server with a cloud front-end that Wendell mentioned before?

A while back when I was less-educated-but-watched-anyway, like many of us have been but gained interest over time, I remember Wendell mentioning in a video that he would either show us how to or did - and I just forgot, on how to set up a home mail server, but have a cloud relay so if the local server isn't on the emails sent wouldn't just dispensary because there was not a destination server.

Does anyone have the video where he mentioned that, or know if he has/will followed up on it?

Any help would be great. :)

Is it this?

I haven't watched the whole thing, but I am pretty sure this is setting up a mail-server with Cpanel, which is in the cloud.

The point of what he said before was hosting on your own hardware, and using a small server box to relay mail in case your local machine can't receive mail at any time.