Mail was unable to open this mailbox on the server “p71-imap.mail.me.com”.

Room101A wrote:

Good grief! If it's not one thing, it's another. Now can't log into my iCloud account; same problem I presume and so will try later. Odd that my wife, on the same LAN, is having no problems with Mail or logging onto her iCloud account

If a Mac, boot into Safe Mode and try again: Start up your Mac in safe mode - Apple Support

If an iPhone or iPad, restart;

Restart your iPhone - Apple Support

Restart your iPad - Apple Support

Do you have any add-on anti-malware, add-on anti-virus, add-on VPN clients, add-on cleaner apps, or add-on network firewall apps? If so, remove those per the vendors’ instructions, reboot, and try again. (iPhone, iPad, and macOS can have different mixes of these apps.)

Update iOS or iPadOS or macOS to current, too.

Hi nf207,

It sounds like you're having issues with Mail. If that's correct, let's try the following.

How to use safe mode on your Mac

See if the issue happens when booted to safe mode.

Cheers.

Apple had server issues yesterday (which doesn’t help with a report from the 5th), and there have been internet-wide routing issues over the past week or three, and well, pretty much forever. At times, it becomes clear the internet is held together with tongue depressors and duct tape, and local networks can be just as flaky.

Here is the Apple server status info, though yesterday’s outside is no longer listed

https://www.apple.com/support/systemstatus/

Here’s a report of one of the recent internet-wide routing issues;

https://www.theregister.com/2021/04/20/vodafone_india_bgp_hijack/

Put differently, yeah, sometimes glitches happen, try again later. If it persists, check your local network, check the Apple server status, and then work your way through the intervening network connection.

About a month after nf207's post, I am experiencing exactly the same problem. I did as suggested and booted in safe mode and the problem persisted. I checked https://www.apple.com/support/systemstatus/ and there were no outages/

This is an enormous PITA when you are as dependent up on email as I am. I hope someone comes up with a solution.

Good grief! If it's not one thing, it's another. Now can't log into my iCloud account; same problem I presume and so will try later. Odd that my wife, on the same LAN, is having no problems with Mail or logging onto her iCloud account.

Go figure ;-)