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Sending mail to contact results in soft reject

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Posted on by HN-16101056-0

We are setting up newsletters with the Consent Center and Compliance profiles.

I add an internal mail-enabled security group as a contact and this contact is included in the segment that holds the newletter recipient; we want our internal users to get the information as well.

Regular sending mechanism: Segment that finds the relevant consents, journey that sends to this segment.

On the Insight on the mail I get this:

Soft reject with "550 5.7.133 RESOLVER.RST.SenderNotAuthenticatedForGroup".

The security group is enabled for external mail.

All other recipient receives the mail (except for the obvious regular - and expected - errors like mailbox full, rejected etc.).

Regards,

Henrik Neumann

Categories:

Dynamics 365 Customer Insights - Journeys

Outbound to Real-Time Transition

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HN-16101056-0 8 on at

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Further information:

The delivery of the newsletter to that mailaddress works in Outbound Marketing.

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Erin Lubben 75 on at

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Thanks for sharing the details of your setup. The error you're encountering:

550 5.7.133 RESOLVER.RST.SenderNotAuthenticatedForGroup typically indicates that the sender is not authorized to send emails to the mail-enabled security group. Even if the group is enabled for external mail, it may still require authenticated senders or specific permissions.

Here are a few steps you can take to troubleshoot:

Review Group Settings in Exchange Admin Center

Confirm that the group allows external senders.

Verify that the sender address used by Customer Insights - Journeys is authorized to send to the group.

Check Mailbox Authentication and Server-Side Synchronization

Ensure that the mailbox associated with the sender is properly authenticated.

Confirm that server-side synchronization is active and functioning for the mailbox. This is essential for outbound emails to be processed correctly

Validate Sender Identity in Customer Insights

Make sure the email sender domain and address configured in your Compliance profile match what the group expects.

Verify Delegate Permissions in Outlook

As a workaround, ensure that the user sending the email has delegate permissions to send on behalf of the mailbox owner.

You can test this by manually sending an email from Outlook using the “From” field and selecting the intended sender. If this works, it confirms that delegate permissions are correctly configured.

Consider Using a Distribution List

If the mail-enabled security group is too restrictive, try using a mail-enabled distribution list instead, which may have fewer delivery constraints.

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HN-16101056-0 8 on at

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Hi,

Thanks for your answer - I will review this and hopefully find a solution - I will provide further information once I have completed the tasks.

Regards,

Henrik

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