Microsoft KB Archive Search

Notice: This website is an unofficial Microsoft Knowledge Base (hereinafter KB) archive and is intended to provide a reliable access to deleted content from Microsoft KB. All KB articles are owned by Microsoft Corporation. Read full disclaimer for more details.

  1. Home
  2. "550 5.7.12," "550 4.4.7," or "420 4.2.0" NDR when a user can't receive email messages through EOP in Office 365 Dedicated/ITAR

"550 5.7.12," "550 4.4.7," or "420 4.2.0" NDR when a user can't receive email messages through EOP in Office 365 Dedicated/ITAR

View products that this article applies to.

Symptoms

In Microsoft Office 365 Dedicated/ITAR, a single user cannot receive web email through Microsoft Exchange Online (EOP) even though directory synchronization is enabled. Additionally, the sender receives a nondelivery report (NDR) that resembles one of the following: 
550 5.7.12 RESOLVER.RST.SenderAuthenticated; Delivery restriction check failed as sender not authenticated

550 4.4.7 QUEUE.Expired; message expired
420 4.2.0 Recipient deferred because there is no Mdb
420 4.2.0 RESOLVER.ADR.Ambiguous; ambiguous address

↑ Back to the top

Cause

This issue occurs if the following conditions are true:
  • The synchronized recipient object in Microsoft Azure Active Directory (Azure AD) is misconfigured.
  • The synchronized recipient object in Azure AD prevents mail routing from reaching the Office 365 Dedicated/ITAR environment. 

↑ Back to the top

Resolution

To resolve this issue, escalate the case to Microsoft. You may submit a support incident online to Microsoft Online Services Support. Or, you can contact Microsoft Online Services Support by telephone .

↑ Back to the top

Keywords: kb, uacrossref, kbcrossrefol, vkbportal250, vkbportal226

↑ Back to the top

Article Info
Article ID : 3028012
Revision : 6
Created on : 11/14/2019
Published on : 11/14/2019
Exists online : False
Views : 694