Security Fridays Quick Tip - Enable 'External' email tagging in Outlook

If you haven’t already done so, you can enable ‘External’ tagging in Outlook for your Microsoft Office 365 tenant. This allows any external emails to be tagged which can be helpful if someone tries to impersonate emails or for attempted Phishing emails. 

Resource: Set-ExternalInOutlook (ExchangePowerShell) | Microsoft Learn

Quite simple to enable:

• Connect to Exchange Online using Powershell
  • Connect-ExchangeOnline -UserPrincipleName user@domain.com
• Check status
  • Get-ExternalInOutlook
• If set to false, to enable
  • Set-ExternalInOutlook -Enabled $true
• To exclude a domain from being tagged:
  • Set-ExternalInOutlook -AllowList “example.com”
• To exclude an email from being tagged
  • Set-ExternalInOutlook -AllowList “admin@example.com”