Error code 550 due to Reject Direct Send feature in Microsoft Exchange


Disclaimer: This article is provided for instructional purposes only. To get more information in regards to these scenarios, we recommend to get in touch with the support team at Microsoft. Issue symptoms
Users within your company's email domain do not receive outgoing emails from your Zendesk account.

Email delivery failure notifications to those recipients include an error of Recipient server rejected email. Status code: 550

Delivery logs show a more specific error of 550 5.7.68 TenantInboundAttribution; Direct Send not allowed for this organization from unauthorized sources.
Your organization has the Reject Direct Send feature enabled in Microsoft Exchange.
These errors occur because your organization's Exchange policies are actively blocking emails from reaching their intended recipients. This happens when Zendesk isn’t recognized as an authorized sender for your external support address. Resolution steps These errors originate from Microsoft, not Zendesk. Your email administrator is responsible for reviewing the error message and verifying your email configuration. However, Zendesk offers basic guidance to help you set up your external email address successfully. To resolve outgoing email delivery issues, ensure your external support address is properly configured and meets all setup requirements: Allowing Zendesk to send email on behalf of your email domain If you continue to experience the issues described in this article, consider one of these solutions:
Directly connect your non-Zendesk Microsoft Exchange-based email servers to your Zendesk Support instance using the Exchange Connector. This allows you to keep the Reject Direct Send setting enabled because with this setup, all email notifications are sent by your own Exchange server. Please note the limitations documented in the article on the Exchange Connector.

Instead of enabling the Reject Direct Setting, use a Transport rule to block, redirect or quarantine undesired emails, and exempt emails from Zendesk from the Rule, as described in the Microsoft FAQs. TheX-Mailer: Zendesk Mailer header may be used to identify mail sent from Zendesk. Your email administrator is responsible for completing this setup, and Zendesk Support cannot provide guidance on its specific configuration.

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Why do users within my company or customer account domain not receive emails from Zendesk Support? Why do email delivery notifications show error "Recipient server rejected email. Status code: 550"? What causes the delivery log error "550 5.7.68 Tenant InboundAttribution; Direct Send not allowed for this organization from unauthorized sources"?
Your company or customer account policies block emails to recipients. This issue occurs when you enable the **Reject Direct Send** feature in Microsoft Exchange and Microsoft Exchange does not recognize Zendesk as an authorized sender for your external support address.

How do I fix the "Status code: 550" email delivery failure? How do I resolve the "Reject Direct Send" error in Microsoft Exchange? How can I ensure users receive emails from my ticketing system or help desk?
Your email administrator must review the error message and verify your email configuration. You can resolve email delivery issues when you ensure your external support address meets setup requirements. Choose one of these options to resolve the issue:

Configure your external support address to allow Zendesk to send email on behalf of your email domain.
Connect your non-Zendesk Microsoft Exchange-based email servers to your Zendesk Support or help desk instance with the **Exchange Connector**.
Use a Transport rule to block, redirect, or quarantine emails, and exempt emails from Zendesk from the rule.


Can I keep the "Reject Direct Send" setting enabled in Microsoft Exchange? Can I use my own Exchange server to send Zendesk notifications?
Yes. You can keep the **Reject Direct Send** setting enabled if you connect your non-Zendesk Microsoft Exchange-based email servers to your Zendesk Support or ticketing system instance. The **Exchange Connector** allows this setup because your own Exchange server sends all email notifications.

How do I identify email notifications sent from Zendesk? How can my email administrator identify mail from Zendesk Support?
Your email administrator can use the **X-Mailer: Zendesk Mailer** header to identify mail from Zendesk. The administrator can use this header to exempt Zendesk mail from a Transport rule.




