Outlook.com: Legitimate Receipt Forwards Now Blocked with 550 5.7.520 “Content Identified as Spam”

Question

I’m having an intermittent problem sending email from my Hotmail account and I believe it’s a false positive in your outbound spam filtering.

When I forward certain purchase receipts from my Hotmail address to my receipt‑processing address ([PII Removed]@verify.cc address which is hosted by Google), the messages sometimes bounce with this NDR:

Generating server: PH0PR10MB4646.namprd10.prod.outlook.com Remote server returned: 554 5.7.0 <#5.7.520 smtp; 550 5.7.520 Message blocked because it contains content identified as spam. AS(4810)>

The receipts are normal transactional emails (for example from Chewy and Instacart), often with HTML content and/or a PDF attachment. I am not sending any bulk mail, marketing campaigns, or unsolicited messages.

Important details:

• This Hotmail account is long‑standing and has been used for years to forward receipts to my Veryfi account without any issues until recently.

Now, only some of these forwards are blocked with 5.7.520, while others go through normally.

The recipient system is legitimate business software (Veryfi), and when I resend similar content from other providers it is accepted without problems.

From what I can find in Microsoft’s own documentation and community answers, 550 5.7.520 ... AS(4810) indicates your outbound spam system is classifying these messages as spam on the Microsoft side. I need help to:

Confirm that this is indeed an outbound spam/false‑positive issue on my account, and

1. Have my account/message pattern reviewed and delisted or adjusted so that legitimate purchase‑receipt forwards (often HTML + PDF) are no longer blocked.

Please let me know what information or sample messages you need (I can provide .eml files of affected messages) and what steps I should take so these legitimate emails can be delivered reliably again.

Thank you.

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 Daniel R

Please confirm:

• Does the bounce happen only when forwarding receipts, or can you reproduce it by sending a brand-new plain email (simple text, no attachments) to the same @verify.cc address? 
• When a receipt is blocked, is it always from the same merchant(s), or is it random across different receipt senders? 

In the meantime, please feel free to try the Q& assistance answer and then tell me how it goes.

I look forward to hearing from you. Have a lovely day!

Answer 2

The error 550 5.7.520 ... AS(4810) indicates that Microsoft’s outbound spam protection is blocking the message because its content is being classified as spam before it leaves the Outlook.com/Hotmail system.

For a consumer Outlook.com/Hotmail account, there is no direct self‑service way to change outbound spam rules, but the following actions are supported and recommended:

1. Collect samples of the failures
   • Save several affected messages as .eml files, including:
     • The original receipt as received in the inbox.
     • The failed forward attempt (including full headers and body).
   • Note the approximate timestamps and the full NDR text, including the 5.7.520 and AS(4810) details.
2. Verify that the content is legitimate and non‑bulk
   • Ensure the forwards are one‑to‑one transactional receipts, not bulk or automated mass forwarding.
   • Remove any obviously spam‑like additions (marketing footers, URL shorteners, etc.) from the forwarded message body where possible.
3. Use Microsoft’s sender support channel for Outlook.com
   • Because this is an Outlook.com deliverability/spam‑classification issue, use the Outlook.com sender support form described under “Troubleshooting tips for IT admins” in the Sender Support in Outlook.com article.
   • That form is explicitly intended for cases where mail complies with Microsoft policies but is still being blocked or misclassified.
   • In the form submission, include:
     • That the account is an Outlook.com/Hotmail consumer mailbox.
     • The exact NDR text (550 5.7.520 ... AS(4810)).
     • The destination domain (Veryfi’s verify.cc address hosted on Google).
     • A description that these are forwarded purchase receipts (HTML + PDF) and not bulk or unsolicited mail.
     • Representative message samples or headers from the .eml files.
4. Continue normal use while Microsoft reviews
   • Outbound spam systems can apply throttling or stricter scrutiny if a pattern looks risky. Keeping usage clearly transactional and non‑bulk helps reputation over time.
   • If Microsoft adjusts the classification, delivery should normalize without further action.

If the problem persists after submitting via the Outlook.com sender support channel and providing samples, repeat with additional recent examples, as the investigation relies on current data.

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References:

• Sender Support in Outlook.com
• Frequently asked questions - Anti-spam protection