Update Test-MtCisaExternalSenderWarning.md

powershell/public/cisa/exchange/Test-MtCisaExternalSenderWarning.md

@@ -2,6 +2,8 @@ External sender warnings SHALL be implemented.
 
 Rationale: Phishing is an ever-present threat. Alerting users when email originates from outside their organization can encourage them to exercise increased caution, especially if an email is one they expected from an internal sender.
 
+> ⚠️ WARNING: This test allows the use of a technical mechanism that differs from CISA's, though the outcome is the same.
+
 #### Remediation action:
 
 ##### Option 1: Use external sender identification
@@ -42,4 +44,4 @@ To create a mail flow rule to produce external sender warnings:
 * [CISA ScubaGear Rego Reference](https://github.com/cisagov/ScubaGear/blob/main/PowerShell/ScubaGear/Rego/EXOConfig.rego#L405)
 
 <!--- Results --->
-%TestResult%
+%TestResult%