Office 365 mail flow troubleshooting index

Not sure what release of Office 365 you're using? Go to the following Microsoft website:

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. 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

• Why is my message taking so long to arrive at its destination?
• Webcast: Troubleshooting issues with sending and receiving email in Office 365
• Webcast: Advanced techniques for troubleshooting issues with sending and receiving email in Office 365
• Webcast: Troubleshooting DNS

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

• Where is the message that someone claims to have sent me?
• Webcast: Troubleshooting issues with sending and receiving email in Office 365
• Webcast: Advanced techniques for troubleshooting issues with sending and receiving email in Office 365
• Webcast: Troubleshooting DNS

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 Backscatterer.org 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

• How do I interpret a Delivery Status Notification (DSN) message?

Mail flow to or from on-premises environments

Knowledge Base articles

• 2510049 On-premises users aren't getting email messages from Office 365 users in an Exchange hybrid deployment

Help and TechNet content

• Shared address space with on-premises relay scenario (MX points to on-premises)
• Shared address space with on-premises relay scenario (MX points to FOPE)

SMTP relay with Exchange Online

Knowledge Base articles

• 2600912�How to set up Exchange Online as an SMTP relay �
• 2799338 How to enable on-premises applications and devices to send mail to Office 365 users

Help and TechNet content

• Fully hosted scenario
• Outbound smart host scenario
• Inbound safe listing scenario
• Regulated partner with forced TLS scenario

Office 365 Community

• Mail flow in Office 365

Still need help? Go to the Office 365 Community website.