Okay brilliant and accomplished Mastodonians and Fediversians, it;'s time I consult the hive mind about self-hosting.
I've started to read up on this topic, but I haven't seen a clear answer to THIS question yet:
If I self-host from a desktop computer, must I keep it on all the time, or can I turn it off when I'm doing other things.
Specifically, will incoming emails get lost if they can't be delivered in a timely fashion?
My thanks again to all you wonderful souls.
#SelfHosting #FediverseHiveMInd

@Guillotine_Jones

An email server which can't reach the only legal destination for a message can hold on and attempt redelivery.

In practice, GMail is likely to declare you don't exist at all, and anyone else will try again in a few minutes and then in a few hours.

You can amend this by designating some other cooperative mail server as a secondary MX for your domain; that mail server will accept delivery and try to deliver to your mail server later on.

It's a nice service to exchange with friends.

@dashdsrdash
Thank you for a very intriguing response, --dsr=.
Your very helpful reply deserves careful scrutiny and sounds like it might provide a solution.