Exchange Online unable send email to error Security or policy settings at have rejected your message.

LEE CHEE KWONG 0 Reputation points

Exchange Online unable send email to error Security or policy settings at have rejected your message.

More Info for Email Admins
Status code: 550 5.7.1

This error occurs when the recipient's domain has security or policy settings that reject the sender's message. However, we were unable to determine the specific setting that's causing this rejection. Usually the error is reported by an email server outside of Office 365. Common issues include the following: the receiving server suspects the message is malicious or spam; the Sender Policy Framework (SPF) record for is incorrectly configured or doesn't exist; or the message includes an attachment larger than the receiving server will accept. Try one or more of the following:

Review the reported error - Check the Reported error shown below to help determine what the issue might be. For example, if the issue is related to an SPF failure, the reported error will usually include the acronym "SPF" or the phrase "Sender Policy Framework."

Correctly configure your SPF records - If you're the sender's email admin, make sure your domain's SPF records at your domain registrar are properly configured. Office 365 supports only one SPF record (a TXT record that defines SPF) for your domain. Include the following domain name: If you have a hybrid configuration (some mailboxes in the cloud and some mailboxes on premises) or if you're an Exchange Online Protection standalone customer, add the outbound IP address of your on-premises servers to the TXT record. To learn how, see Customize an SPF record to validate outbound email sent from your domain and External Domain Name System records for Office 365.

Unable to relay - If the Reported error indicates a problem with relaying (e.g. "unable to relay"), then the email server that reported the error likely isn't set up correctly to receive and relay messages from the sender's domain. This server will usually be one of your on-premises servers in a hybrid environment, a smart host email service that you're trying to route messages through, or possibly even an email hosting service you used in the past yet still have mail flow settings pointing to (e.g. your MX record at your domain registrar still points to your previous email service provider). Check Error reported by shown below to determine what domain, service, or server is reporting the error. The email server needs to be configured to either accept messages from anonymous users or to include the sending domain or IP in its list of authenticated senders. On an Exchange server, you can set this up in the server's receive connector. If it's a smart host managed by another service or partner, contact the service or partner to configure their servers to accept and relay messages from your senders. Also, work with your domain registrar to make sure your MX records are properly configured.

Contact the recipient's email admin - For some scenarios, you can fix the issue by contacting the email admin at the recipient domain to ask them to add the sender's email address or your domain to their allowed senders list, or to relax the setting that's causing the rejection.

For more information and tips for fixing this issue, see Fix email delivery issues for error code 5.7.1 in Office 365.|

Microsoft 365
Microsoft 365
Formerly Office 365, is a line of subscription services offered by Microsoft which adds to and includes the Microsoft Office product line.
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