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 5.7.1" NDR when you send messages to external recipients in an Exchange Server 2013 hybrid environment

"550 5.7.1" NDR when you send messages to external recipients in an Exchange Server 2013 hybrid environment

View products that this article applies to.

Symptoms

Consider the following scenario:
  • You have a Microsoft Exchange Server 2013 hybrid environment.
  • You install Cumulative Update 6 on the on-premises Exchange Server 2013 server.
  • You enable centralized mail transport in the hybrid deployment.

    Note Centralized mail transport routes outgoing email messages from the Exchange Online mailboxes through your on-premises Exchange servers. For more information, see Transport routing in Exchange 2013 hybrid deployments.
  • A user whose mailbox is located in Office 365 sends an email message to an external recipient.
In this scenario, the email message is not delivered successfully, and the user receives a non-delivery report (NDR) that contains the following error message: 
550 5.7.1 Unable to relay

↑ Back to the top

Cause

This issue occurs because centralized mail transport does not work in Cumulative Update 6.

↑ Back to the top

Resolution

To resolve this issue, install Cumulative Update 7 for Exchange Server 2013. 

↑ Back to the top

Status

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

↑ Back to the top

Keywords: kbsurveynew, kbexpertiseadvanced, kbqfe, kbfix, kb

↑ Back to the top

Article Info
Article ID : 3003518
Revision : 1
Created on : 1/7/2017
Published on : 12/9/2014
Exists online : False
Views : 216