Deliverability issue with Outlook.com

Question

Deliverability issue with Outlook.com

CrystalH 0

Dear Microsoft,

Outlook.com email accounts are rejecting emails from our registered charity. We recently upgraded our website hosting and email plan with Namecheap from the basic plan to the business plan, and our email and hosting were moved to a different server and IP address [Moderator's note: personal info removed].

Ever since, we are not able to send emails to outlook.com email accounts.

Here is the bounce back email:

Delivery has failed to these recipients or groups:

____@outlook.com A problem occurred while delivering your message to this email address. Try sending your message again.

The following organization rejected your message: outlook-com.olc.protection.outlook.com.

Diagnostic information for administrators:

Generating server: [Moderator's note: personal info removed]

______@outlook.com outlook-com.olc.protection.outlook.com Remote server returned '554 5.0.0 <outlook-com.olc.protection.outlook.com #5.0.0 smtp; 550 5.7.1 Unfortunately, messages from [Moderator's note: personal info removed] weren't sent. Please contact your Internet service provider since part of their network is on our block list (S3150). You can also refer your provider to [http://mail.live.com/mail/troubleshooting.aspx#errors][Moderator's note: personal info removed] Click or tap to follow the link."). [Moderator's note: personal info removed]>'

Original message headers:

Return-Path: <____@domain.ca>

Received: from

by

        (Exim 4.99.4)

        (envelope-from <_____@domain.ca.)

id

        for _____@outlook.com

        Tue, 28 Jul 2026 00:13:22 -0400

From: ",_____@domain.ca>

To: ______@outlook.com

Subject: test 11:13pm

Thread-Topic: test 11:13pm

Thread-Index:

X-MS-Exchange-MessageSentRepresentingType: 1

Date: Tue, 28 Jul 2026 04:13:22 +0000

Message-ID: <

Accept-Language: en-US

Content-Language: en-US

X-MS-Has-Attach:

X-MS-Exchange-Organization-SCL: -1

X-MS-TNEF-Correlator:

X-MS-Exchange-Organization-RecordReviewCfmType: 0

msip_labels:

Content-Type: multipart/alternative;

 boundary="_000_SA1PR22MB5501BBB56B0E85E91B5CD4A9ADCB2SA1PR22MB5501namp_"

MIME-Version: 1.0


Are you able to delist our email please? I already wrote [delist@microsoft.com](mailto:

Thank you,  
[Moderator's note: personal info removed]

0 comments

1 answer

Your answer

Answer 1

Dear @CrystalH,

To request assistance with error code S3150, please submit a support request through the New support request. The specialized support team will review your case and assist you with the appropriate unblock process.

You may also refer to the Troubleshooting for additional information regarding this type of delivery issue.

User's image

Please note that the unblock request must be submitted through the support portal linked above. Unfortunately, this process cannot be completed through general community or forum platforms.

I hope the information shared helps point you in the right direction.

As a moderator, I do not have the tools to investigate your specific account directly, as this is a support forum between users. Moderators and collaborators, including external Microsoft employees, may not directly intervene in the functionality of Microsoft products or access internal systems. Our role is limited to providing technical guidance on reported problems, requests, or ideas. However, I will do my best to guide you as clearly as possible.

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