Microsoft Exchange no longer support High Sierra

I only have one, and my outlook.com account is set to retrieve email from my domain.

One thing GoDaddy may not tell you is that if Outlook.com grabs your email, Outlook has an email quota which if you don't pay for a Microsoft license, stops checking email on Exchange. I would tell GoDaddy that IMAP works just fine on Catalina and Mojave. I use both. If you want to upgrade just to Mojave, most Macs that run High Sierra can run Mojave without changing compatibility.

Upgrading to Mojave (Mac OS 10.14) - Apple Community

Yes, I never had issues with IMAP or POP either until Godaddy advised us all we had to update to Exchange.

This account on my Mac Mail on my Big Sur v 11.6.8 will no longer synch and display new emails. It is identified as an imap-mail.outlook.com host. I may be confused is there a difference between Outlook and Exchange? They are both Microsoft based and all I can say is that until yesterday, this account downloaded my messages but now it's not and it when I enter the password which I know is correct, it give me the message you see.

All my other Godaddy email accounts are on imap.secureserver.net which works fine. But if I change my settings for this account back to imap.secureserver.net it still won't work.

Obviously I don't want to make a misstep and lose all the archived email on my server I relay on so thanks if you can help.

Just found this article I am looking at now which shares my recent experience but I'm also assuming the timing of this email had something to do with things.

https://appletoolbox.com/fix-apple-mail-not-syncing-with-exchange/#:~:text=Update%20Mail%20App%20and%20Switch,on%20iOS%20devices%20as%20well.

BTW I have Outlook on my iPhone to see messages which are downloading fine as I think it was awhile back my Mac Mail wouldn't sync on my iPhone which is what precipitated the change.

As far as MFA, I don't know if Exchange offers the same solution as iCloud for older systems, but iCloud can have the MFA code inserted after the password when logging in an MFA attempt is made into iCloud accounts. Alternatively you can have your Microsoft Authenticator App on your phone set up for the MFA account and waiting your login on your computer. There you can confirm the login is good.

Big Sur won't make a difference... I'm on it and am now faced with the same predicament. This isn't an Exchange issue... it's an Apple one. I was told by Godaddy that I would have to update my system to OS 14 because Apple wasn't providing Mac Mail support to coexist with the Exchange two step verification. And I am not changing my entire OS and updating all my software that works fine now I don't want to pay for again. Although why we couldn't stick with the old POP system in the past is beyond me... none of these updated verifications that are supposed to provide more security actually do so. I can't stand having to use my browser to access my mail and will now have to figure out how to add my personalized signature there. Ironically, none of my other Mac mail accounts are suffering this issue, but Godaddy promised in time Mac will screw us there too as they will have an expiration date functioning soon. Thanks Apple!

IMAP is better than POP in that multiple devices can use it simultaneously without duplciation, although if you want to ensure a message isn't lost, you'll need to copy it to a local folder and backup that local folder. Use the Other... account to configure your account as IMAP.

Exchange is a Microsoft standard. If they change anything to do with it, they need to provide Apple with the keys to do it. Keep in mind Microsoft isn't supporting older versions of Office on older Mac OSes. Eventually thanks to the job industry if you want a formatted résumé you will need a newer OS. No open source versions of Word maintain Office layout standards. Not even the free Office 365 web version.

http://www.outlook.com/ will allow you to access Exchange servers on the web.

You may need a more compatible browser than you presently have.

Browsers by Mac operating system - Apple Community

Exchange Settings also with the correct password that works in Outlook Browser but not Mac Mail.

This is the Mac Mail Exchange Account that has not updated incoming mail since October of last year.