Apple Mail not working after disabling Legacy Authentication – Exchange Online

If just enabled a Conditional Access Policy blocking legacy authentication to Exchange Online, enabled Security Defaults, or Microsoft disabled it for your tenant, you might see some Apple Mail clients not connecting anymore.

This issue is happening because the profile might be still configured to use Exchange ActiveSync to connect to Exchange Online, and EAS (along with other legacy protocols) will be retired in October 2022.

Apple supports an automatic switch to modern authentication for its profiles, but only if it was freshly configured after iOS 12.

Unfortunately, it seems that backing up and restoring profiles does not trigger the switch to modern auth, so if you moved to a new iPhone and didn’t reconfigure the profile manually, you’ll need to remove and recreate it.

UPDATE 16.06.2022:

Apple will add support for the automatic migration to modern auth in iOS 15.6. Once you update your Apple device, the Mail app will use the saved credentials to establish a new authentication flow. From that moment onward, you’ll authenticate to Azure AD (Microsoft online Identity Provider) and get a new OAuth access token. The “old” stored credentials will then be removed. The process is fully transparent to users.

Read the full announcement here: Microsoft and Apple Working Together to Improve Exchange Online Security

Enable Unified Audit Logs – Office 365

Unified Audit Log is one of the essential features for tracking down every action done across the tenant.

The logs are kept for 90 days by default, but you can extend them using special addons.

If you want to check whether the logging is enabled on your tenant, connect to Exchange Online with PowerShell. Once connected, you can check the status.

Install-Module ExchangeOnlineManagement
Import-Module ExchangeOnlineManagement
Connect-ExchangeOnline -UserPrincipalName
Get-AdminAuditLogConfig | FL UnifiedAuditLogIngestionEnabled

If you get “True” as a result, the logging is enabled. If you get “False”, follow the steps below to enable it:

PowerShell way:

Using the PS tab, you opened before to check the Audit Log status, send the following command:

Set-AdminAuditLogConfig -UnifiedAuditLogIngestionEnabled $true

You might be asked to run “Enable-OrganizationCustomization” before relaunching the command. You must wait 30 to 60 minutes after sending “Set-AdminAuditLogConfig -UnifiedAuditLogIngestionEnabled $true” to see it enabled in the portal.

Portal way:

Go to, then click on “Audit” on the left pane. When you get to the page, click on “Start recording user and admin activity“, then check the status after 30-60 minutes. If it fails, try with PowerShell.

Change Outlook profiles from one month cache to online in AVD/WVD

Unfortunately, at this time, there is no way to change Outlook profiles from cached mode (1 month retention) to online mode in the Outlook settings.

To configure the cache settings in Outlook (2016/365) in a WVD session you need to use Active Directory GPOs or local Group Policies.

To use local group policies follow these steps:

  • Download the following ADMX in your environment:
  • Extract the files
  • Copy the outlk16.admx file to %systemroot%\PolicyDefinitions\
  • Based on the language folders you see in your WVD host copy the outlk16.adml file from the admx\xx-xx folder to the relative folder in %systemroot%\PolicyDefinitions\
  • Open gpedit.msc
  • Go to User Configuration > Administrative Templates > Microsoft Outlook 2016 > Account Settings > Exchange > Cached Exchange Mode.
  • Set “Use Cached Exchange Mode for new and existing Outlook profiles” to Disabled