Email Delivery Failure from Exchange Online to Gmail - 550 5.7.1 Low Reputation Error

Question

Email Delivery Failure from Exchange Online to Gmail - 550 5.7.1 Low Reputation Error

Vladyslav 0

Description:
We are unable to deliver emails from our Microsoft 365 (Exchange Online) domain to Gmail recipients. Emails are rejected by Gmail with the following NDR (Non-Delivery Report) error:

"550-5.7.1 [[Moderator note: personal info removed]] Our system has detected that this message is likely spam, and it has been rejected. The reason for the rejection is: very low reputation. Please visit https://support.google.com/mail/?p=LowReputation to diagnose and fix the issue. While you have been sending mail with low reputation, we have detected that this message is likely spam and it has been rejected. Please visit https://support.google.com/mail/?p=LowReputation to diagnose and fix the issue. PC Order: [Moderator note: personal info removed]"

This issue started on [date, e.g., November 12, 2025] and affects all outbound emails to @gmail.com addresses. It is severely impacting our business communications (e.g., customer support, invoices).

**Troubleshooting steps we've taken:**
- DNS authentication verified: SPF record includes "include:spf.protection.outlook.com" (passes MX Toolbox check), DKIM enabled and verified (selector: [your selector, e.g., selector1._domainkey]), DMARC policy set to quarantine (p=quarantine; rua=mailto:******@yourdomain.com).
- No bulk or high-volume sending; emails are legitimate business/transactional (low volume, no suspicious content/attachments).
- Checked Exchange Online Message Trace: Messages are sent successfully from our side, but bounced by Gmail. No policy violations, malware, or spam filters triggered in M365.
- Domain registered in Google Postmaster Tools: Shows low spam complaint rate (under 0.1%), but overall reputation flagged as low.
- IP range: Using Microsoft 365 outbound IPs (e.g., 40.92.x.x/13) – not listed in major DNSBLs (verified via Talos Intelligence).
- Submitted delisting request to Google (via support.google.com/mail/contact/delisted), but awaiting response.

Request:
Please investigate this on Microsoft's end: Confirm if our tenant/IP has any reputation issues with Google, check for any outbound connector problems, or escalate to Google for whitelist review. We need urgent resolution as this blocks ~[X]% of our external emails.

Details:
- Affected domain: [Moderator note: personal info removed].com.ua
- Bounce ID: PC Order [Moderator note: personal info removed]
- Attached: Screenshots of bounce message, DNS verification results, and Message Trace log.

Priority: High – Business-critical.

Thank you for your assistance.

Комментариев: 0

1 ответ

Ваш ответ

Answer 1

Please note that this is the ru-ru forum. We kindly recommend posting your question in Russian so that more community members can assist you. Alternatively, you may consider posting in the English forum if you prefer to use your native language. We sincerely appreciate your understanding.

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.

Hi @Vladyslav

Thank you for reaching out to Microsoft Learn Q&A!

To help investigate the issue with your low-reputation domain, I strongly recommend reaching out directly to the Microsoft Support Team. They are in the best position to assist you compared to the limited resources available to forum moderators like myself.

Here are two official ways to contact Microsoft Support:

Option 1: Contact via Phone

You may need to reach out via the customer service phone number: Customer service phone numbers - Microsoft Support.

Important Note: You may first interact with an AI assistant before being connected to a human agent. Please answer the questions carefully to ensure you're routed correctly. Having your information ready will help speed up the process.

Please be aware that this team is often handling a high volume of cases. It may take 3–10 business days for them to get back to you.

Option 2: Raise a ticket via the Microsoft 365 Admin Center

You can submit a support request through the Microsoft 365 Admin Center. For step-by-step guidance, please refer to: Get support - Microsoft 365 admin | Microsoft Learn

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I sincerely hope this information helps clarify your situation and supports you in planning your solution. Please don’t hesitate to reply if you have any updates.

Thank you for your understanding.

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