Quarantine new outlook connections

1. Quick self-check
Check account status
Sign in to Microsoft 365 Security Center
Go to “Audit Logs” to see if a security policy was triggered
 Test the underlying connection
Access Outlook web version
If you can log in → the problem may be in the client configuration.
2. Common fixes
 Unquarantine the account from administrator action:
Go to Exchange Management Center > Protection > Quarantine
Locate the quarantined account > select “Release”
User self-help (if allowed):
Follow secure email prompts (usually requires authentication)
 Reset Client Configuration
Delete an existing account:
New Outlook > Settings > Accounts > Remove Problem Accounts
Re-add the account:
Use Advanced Settings to manually enter the server address
3. Enterprise Administrator Actions
 Adjusting Security Policies
Go to Microsoft 365 Defender > Policies > Isolation Policy
Modify the following settings:
Reduce the “New Device Login” sensitivity
Exclude corporate IP segments
 Check CASB/MDM restrictions
Verify that third-party security tools (e.g. Cloud App Security) are not blocked
4. Ultimate Solution
 Completely reset the client
Close Outlook
Delete the configuration folder:
~/Library/Group Containers/UBF8T346G9.Office/Outlook/  
Restart and configure