How do I post "Out of Office" dates on my email to notify emails received from others

You can set up a rule in the Mac email application: https://www.howtogeek.com/294111/how-to-set-up-an-out-of-office-reply-in-apple-mail-for-mac/

Although iCloud Mail does permit auto-reply, it will do so to anyone sending an email to your @me.com address, including Spammers. Apple Mail on the Mac has a means to auto-reply to only those sending from a @me.com address by creating a new Mail rule. Let's call that rule auto-reply, and here is what is in it:

When you click that Reply message text… button, you enter your message:

and when you save your new rule, do not authorize it to apply to all current messages, or you will have a mess.

Another rule variation would be from an @me.com address and is in your contacts.

Now, when an email arrives from a @me.com address, it will be automatically replied to with your Reply message at the top of the reply.

Set up an automatic reply in Mail on iCloud.com

Log into www.icloud.com and Mail and look for some setting in there to Send an Out of the Office to new received e-mail.

Caution - doing so will confirm to Spammers that this Address is is active and correct.

Thusly, could potentially increase the amount of Spam Received in the future.

There is no such setting, I checked prior to answering. There was a day where you this was a risk with spammers but those days are long gone. They buy mailing lists from the dark web and don't really care if it is active and correct. It won't increase the amount of spam received.

Perfect, although I went with a different source.

And now everyone just has to hope the aren’t on any mailing lists. Those were the days.

As emphatic and answer as " There is no such setting, I checked prior to answering." I was beginning to worry I had lost my mojo :-)

You will never lose your mojo…me on the other hand…

LOL - doubtful :-))