I received an email stating Update your sign-in technology before September 16th, 2024 to maintain email access. Is this legit or a scam?

The Outlook iPhone app will have no issues. If you're using the Apple Mail app:

If you use Apple Mail:

Apple Mail supports Modern Authentication by default when you setup the account as Outlook.com. If you use Apple Mail and you are seeing password prompts or connection errors, this is most likely happening because your account got configured as basic authentication. To mitigate the issue, remove the account and add it back as Outlook.com:

1. Go to Settings> Mail> Accounts.
2. Tap the email account you want to remove from your iPhone, then tap Delete Account. For more information, please go to Add and remove email accounts on iPhone.

Add your account back to Apple Mail:

1. Go to Settings > Mail.
2. Tap Accounts, then tap Add Account.
3. In the Add Account dialog, choose Outlook.com.
   

If removing and re-adding the account does not address the issue, do the following: 

1. Remove the account again.
2. Go to Settings> Safari, then tap Clear History and Website Data.
3. Reboot your iPhone.
4. Add the account back and proceed through the Outlook.com account sign in flow.

I agree with what you said. I just want to understand in layman terms what is needed so I can get me emails. Thank You!

Whatever is on an iPhone? How do I figure it out? I also downloaded the outlook app from the Apple Store. Will I still be able to get my emails?

No, sadly, not enough. msn is an email SERVICE, not an email CLIENT. How do you connect to msn, Classic Desktop Outlook, Outlook New, Outlook on the web (OWA) through a web browser, Thunderbird, Apple Mail, EM Client, something else?. If you are using Classic Desktop Outlook, Thunderbird, EM Client or something else, what VERSION is it? I see you connect vis IMAP which may be an issue depending on the version of whichever client you use. I can tell you that if you use either Outlook New or Outlook on the Web, there is zero point zip dot nada that you need to do.

My email is msn.com. My host is imap-mail.outlook.com. Is that enough info?