Merge pull request #2261 from MicrosoftDocs/portals-ICMtask1635814-b2cauth

Portals ICM 157826968 task 1635814 b2cauth

Author: KumarVivek

powerapps-docs/maker/portals/configure/azure-ad-b2c.md

@@ -2,13 +2,13 @@
 title: "Azure AD B2C provider settings for portals | MicrosoftDocs"
 description: "Instructions to enable Azure AD B2C provider settings for portals."
 author: sbmjais
-manager: shujoshi
+manager: kvivek
 ms.service: powerapps
 ms.topic: conceptual
 ms.custom: 
-ms.date: 10/18/2019
+ms.date: 01/03/2020
 ms.author: shjais
-ms.reviewer:
+ms.reviewer: tapanm
 ---
 
 # Azure AD B2C provider settings for portals
@@ -513,8 +513,12 @@ The claim name is the CLAIM TYPE field listed next to the attribute in the sign-
 
 ### Allow auto-association to a contact record based on email 
 
-Customers who have contact records with emails associated then launch a website where their external users will sign in with [!include[Azure](../../../includes/pn-azure-shortest.md)] AD B2C through an email validation mechanism. The new sign-in should be associated with the existing contact record instead of creating a duplicate record. This functionality only successfully maps a contact that does not have an active identity, and the email address must be unique (not related to multiple contact records). The following site setting is required:
+Customers who have contact records with emails associated then launch a website where their external users will sign in with [!include[Azure](../../../includes/pn-azure-shortest.md)] AD B2C through an email validation mechanism. The new sign-in should be associated with the existing contact record instead of creating a duplicate record. This functionality only successfully maps a contact that does not have an active identity, and the email address must be unique (not related to multiple contact records). The following site settings are required:
 
 **Name**: Authentication/[Protocol]/[Provider]/AllowContactMappingWithEmail
 
-**Description**: Specifies whether contacts are mapped to a corresponding email. When set to true, this setting associates a unique contact record with a matching email address, and then automatically assigns the external identity provider to the contact after the user has successfully signed in. By default, it is set to false.
+**Description**: Specifies whether contacts are mapped to a corresponding email. When set to true, this setting associates a unique contact record with a matching email address, and then automatically assigns the external identity provider to the contact after the user has successfully signed in. By default, it is set to *false*.
+
+**Name**: Authentication/UserManager/UserValidator/RequireUniqueEmail
+
+**Description**: Specifies whether a unique email address is needed for validating the user. When an existing contact email address is used to sign-in, the setting must be set to false. By default, it is set to *true* that may cause sign-in attempts to fail for contact records with email address already present.