Sent emails are bouncing back

Question

Many of my sent emails are bouncing back. Email response from Live Mail below. Can anyone help?

Delivery has failed to these recipients or groups:

<Mod remove PII> @gmail.com A problem occurred while delivering your message to this email address. Try sending your message again. If the problem continues, please contact your email admin.

The following organization rejected your message: [Moderator note: personal info removed].

Diagnostic information for administrators:

Generating server: **[Moderator note: personal info removed].**livemail.co.uk

<Mod remove PII> @gmail.com [Moderator note: personal info removed] Remote Server returned '554 5.0.0 <[Moderator note: personal info removed] #5.0.0 SMTP; 550 5.7.26 Your email has been blocked because the sender is unauthenticated. 5.7.26 Gmail requires all senders to authenticate with either SPF or DKIM. 5.7.26 5.7.26 Authentication results: 5.7.26 DKIM = did not pass 5.7.26 SPF [[Moderator note: personal info removed] with ip: [Moderator note: personal info removed] = did not 5.7.26 pass 5.7.26 5.7.26 For instructions on setting up authentication, go to 5.7.26 https://support.google.com/mail/answer/81126#authentica tion ffacd0b85a97d-43970d6fe03si14264889f8f.224 - gsmtp>'

Original message headers:

Received: from 

    by 

    with ESMTPS id s0001321NDxj607

    for <

[Moderator note: personal info removed]

Received: from 

    by 

    with ESMTPS id s0001321NDxj607

[Moderator note: personal info removed]

[Moderator note: personal info removed]

    for <

Received: from 

[Moderator note: personal info removed]

[Moderator note: personal info removed]

[Moderator note: personal info removed]

Received: from 

[Moderator note: personal info removed]

[Moderator note: personal info removed]

From: 

To: "

Subject: Test email

Thread-Topic: Test email

Thread-Index: 

Date: 

Message-ID: <

Accept-Language: en-GB, en-US

Content-Language: en-US

[Moderator note: personal info removed]

[Moderator note: personal info removed]

[Moderator note: personal info removed]

[Moderator note: personal info removed]

[Moderator note: personal info removed]

Content-Type: multipart/alternative;

 boundary="

MIME-Version: 1.0

Content-Transfer-Encoding: 7bit

Answer 1

Please note that our forum is a public platform, and we will modify your question to hide your personal information in the description. Kindly ensure that you hide any personal or organizational information the next time you post an error or other details to protect personal data.

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Hi Sarah Barnes

Thank you for reaching out to Microsoft Q&A Forum and sharing your experience.

Based on the Non-Delivery Report (NDR) you provided, the messages are being rejected due to missing or failing email authentication on the sending domain. The error indicates that the message is sent from a custom domain, but routed through a third-party mail server, and the required authentication checks (SPF and DKIM) do not pass. This points to a DNS configuration issue on the sending domain, not a problem with the Outlook client itself.

To resolve this, please contact the email administrator or hosting provider for the sending address, share the error message with them, and ask them to:

• Verify that a valid SPF record is configured and includes the correct sending servers
• Enable and properly configure DKIM signing for the domain
• Consider configuring DMARC to align SPF and DKIM authentication

Once these records are updated successfully (DNS changes may take some time to propagate), Gmail should accept the messages normally.

Please let me know how things go on your side as your update can also assist others in the community who may be facing the same issue.

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