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Article ID: 2757871 - Last Review: July 13, 2014 - Revision: 31.0

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This article contains links to technical resources and support information for troubleshooting mail flow in Office 365.

To troubleshoot common mail flow issues in Office 365, see the Mail Flow Guided Walkthrough (;en;3568&showpage=1) . The walkthrough helps admins to diagnose and resolve issues that are related to mail flow in various scenarios.


Before you review the resources in this article, be aware that the Microsoft Remote Connectivity Analyzer ( offers several tests on the Office 365 tab that are helpful when you are troubleshooting mail flow in Office 365. These tests include the following:
  • Office 365 Exchange Domain Name Server (DNS) Connectivity test
  • Inbound SMTP Email test
  • Outbound SMTP Email test
The following resources discuss mail flow.

Cannot send email messages

Knowledge Base articles
  • 2269971  ( ) Users receive Send/Receive error messages after they configure multiple accounts in Office 365 by using Outlook
  • 2617114  ( ) You can't send email messages in Office 365 Small Business from a domain that's set up for full redelegation
Office 365 Community

Cannot receive email messages

Knowledge Base articles
  • 2415053  ( ) Email messages are not received for a new domain that you add in the Office 365 portal
  • 2526164  ( ) You're not receiving email messages in Office 365 Small Business for a domain that's set up for full redelegation
  • 2598485  ( ) Domain users cannot receive email messages through Forefront Online Protection for Exchange
Office 365 Community

Email delivery delay

Knowledge Base articles
  • 2624610  ( ) Outgoing message delivery is delayed or rejected in Forefront Online Protection for Exchange and you receive a "Greylisting in action, 451 4.7.1" nondelivery report
  • 2625239  ( ) Email messages are deferred in Forefront Online Protection for Exchange (FOPE) when they are sent to a mail server that is deployed behind a Cisco PIX firewall

Nondelivery reports (NDRs)

Knowledge Base articles
  • 2590562  ( ) Users in a FOPE environment receive NDRs when they send mail to a recipient environment that uses the service
  • 2625264  ( ) "550 4.4.7 QUEUE.Expired; message expired" NDR message when you send an email message through FOPE to an external domain
  • 2603474  ( ) "Relay Access Denied" or "Hop Count Exceeded" non-delivery report (NDR) error message when users send mails to Office 365 users
  • 2685437  ( ) "Delivery has failed" and "550 5.1.1 RESOLVER.ADR.RecipNotFound" NDR after a mailbox is moved to Office 365
Office 365 Community

Mail flow to or from on-premises environments

Knowledge Base articles
  • 2730609  ( ) On-premises users aren't getting email messages from Office 365 users in an Exchange hybrid deployment
Help and TechNet content

SMTP relay with Exchange Online

Help and TechNet content
Help and TechNet contentOffice 365 Community
  • Mail flow in Office 365 (
Still need help? Go to the Office 365 Community ( website.

Applies to
  • Microsoft Exchange Online
o365 o365022013 KB2757871
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