Incoming Mail Server Broken for Older Software Versions iMac Timed Out

Is anyone else experiencing issue receiving emails in Mail since Apple changed something 1-2 days ago? I have a 2013 iMac that I am not ready to replace. I hoping to be able to use it for just a bit longer. I stopped upgrading the OS when it started causing issues with apps. Everything is working great except for this one issue. I do not wish to use the icloud.com interface on a browser. It is not as user friendly. I spoke with two Apple reps yesterday that said they could no longer support my products and could not help me with the issue. The error I get is:

"There may be a problem with the mail server or network. Verify the settings for account “iCloud” or try again.

The server returned the error: Connections to the server “p68-imap.mail.me.com” on the default ports timed out."

I can send email so the outgoing server is still mysteriously working. I have already done a lot of trouble shooting. Also, most of the fields in preferences/accounts/iCloud IMAP are now greyed out so I cannot change them.

Anyone find a workaround? I know I am not the only one with this issue and the desire to keep using older equipment.

Oh, by the way, the incoming mail is working fine on my newer MacBook, iPad and iPhone with updated software!