I've updated my security settings in microsoft 365 and now my email won't download to my Apple Mail

Changing security settings in Microsoft 365 can require re-authentication or different connection methods, which can stop Apple Mail from syncing until the account is updated or re-added with the correct settings.

Try these steps on the Mac using Apple Mail and macOS Mail settings:

1. Re-enter Microsoft 365 credentials
   1. Open the Settings app on the Mac (System Settings/System Preferences depending on version).
   2. Go to Apps > Mail > Mail Accounts (or the equivalent Mail accounts section).
   3. Select the Microsoft 365/Exchange account and re-enter the updated username/password when prompted.
2. If re-entering credentials does not work, remove and re-add the account
   1. Open the Settings app.
   2. Go to Apps > Mail.
   3. Select Mail Accounts > Exchange (the Microsoft 365 account).
   4. At the bottom, choose Delete Account.
   5. Still in Apps > Mail, select Mail Accounts > Add Account.
   6. Choose Microsoft Exchange and sign in with the updated Microsoft 365 credentials.
3. If automatic setup fails, configure via IMAP/SMTP
   1. Open Mail on the Mac.
   2. Choose Mail > Add Account.
   3. Select Other Mail Account > Continue.
   4. Enter name, Microsoft 365 email address, and password, then Sign In.
   5. If Unable to verify account name or password appears, select Next and enter settings manually:
      • Email Address and User Name: full Microsoft 365 email address
      • Password: Microsoft 365 password
      • Account Type: IMAP (recommended)
      • Incoming Mail Server: outlook.office365.com
      • Outgoing Mail Server (SMTP): smtp.office365.com
   6. Click Sign In, then choose the apps (Mail, Notes) to use with the account and click Done.
4. Make sure the Microsoft 365 account is active and registered
   • If the account type requires registration, sign in once via Outlook on the web, then sign out and try adding the account again in Mail.

If the account still does not connect after these steps, contact the organization’s help desk or admin, as additional security policies (such as conditional access or modern authentication requirements) may need configuration.

References:

• Reconnecting your Microsoft 365 account to Apple Mail
• Set up email in Mac OS X Mail
• Server settings you'll need from your email provider
• Modern Authentication Methods now needed to continue syncing Outlook Email in non-Microsoft email apps