How to fix this a 550 5.7.520 Message blocked, identified as spam. AS(4810)

Dear Vencent Johnson,

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

I understand you're experiencing an issue where your emails with PDF attachments are failing to deliver, and you're receiving the error message "550 5.7.520 Message blocked because it contains content identified as spam. AS(4810)". I know how frustrating it can be when critical emails aren't delivered, especially when this was previously not an issue.

This error indicates that the recipient's email provider is identifying your message, specifically due to the PDF attachment, as spam or potentially unwanted content, and is therefore rejecting it. This is a common challenge, as email providers constantly update their security filters.

Let's work together to resolve this. Here are a series of steps you can take to address it:

Actionable Steps to Resolve the Issue

Step 1: Communicate with the Recipient Directly

• Reach out to the recipient using an alternative method (phone, text message, or another email address if you have one).
• Inform them about the blocked email.
• Ask them to:
  • Check their Spam/Junk Folder: The email might be there, even if you received a delivery failure notice.
    • Add your email address to their Safe Senders List or Contacts: This tells their email system to trust your emails.
      • Temporarily adjust their spam filter settings (if they are comfortable and able to do so) to allow your email.

Step 2: Modify Your Email and PDF Attachment

• Upload and Share via Cloud Service (Workaround):
• Instead of attaching the PDF directly, upload it to a cloud storage service like OneDrive (if you use Microsoft 365), Google Drive, or Dropbox.
• Generate a shareable link to the PDF and include this link in your email body.
  • Why this helps: This bypasses the direct attachment scanning by email servers, as you're only sending a link. Ensure the link permissions allow the recipient to view/download the file.
• Rename the PDF File: Use a unique and descriptive filename that does not sound generic or suspicious.
• Review PDF Content for "Spammy" Elements:
  • Scan the text within the PDF for keywords often associated with spam
  • Check any links within the PDF. Ensure they are to reputable sites and are not broken or redirecting. If possible, consider removing non-essential links.
  • Simplify the Email Body:
    • Try sending the email with a plain text body (avoiding extensive formatting, large images in signatures, etc.) and only the attached PDF. Sometimes, the combination of a complex email body and an attachment can increase the spam score.
    • Adjust Your Subject Line: Keep it clear, concise, and professional. Avoid all caps, excessive punctuation, or overly promotional language.

Step 3: Test Sending

• After making changes, send a test email with the modified PDF (or cloud link) to your own personal email address (preferably one on a different provider like Gmail or Yahoo, not your work Outlook account). This will help you see if your changes were effective before re-sending to the original recipient.

If the Issue Persists

If you've tried all the above steps and are still facing rejections, please provide the following information so I can investigate further:

• The exact, complete text of any new error messages you receive.
• The recipient's full email address.
• The approximate file size of the PDF.
• Confirmation of which steps you've already attempted.

Please let me know if you find this proven useful and if further assistant is needed.

I appreciate your patience and understanding and I appreciate your time and cooperation. Have a nice day!

Warm Regards,

Kal Duong | Microsoft Q&A Support Specialist

I am facing the same problem. I have no formatting nor attachments, yet my emails are bouncing. This is happening even on chains of emails where I have been succesfully corresponding with people for weeks.

I am having the similar problem as Alex McDonald listed above. It seems I can receive emails okay but I cannot seem to send out emails to the vast majority of people even if I put them into my contact list. I have standard training messages that I have sent out for years to multiple recipients at once and never have had a challenge until recently. I keep getting the bounce back as listed below. It doesn't matter if I send my messages to one person or multiples at the same time. I am not that computer savy but have tried to follow trouble shooting and remedy instructions but most of this is beyond me (I am 70 yrs old). Any guidance and assistance is welcome. Also, just in case, my alternate email is ******@hotmail.com. Thanks for your help in advance.

Diagnostic information for administrators:

Generating server: MW6PR01MB8381.prod.exchangelabs.com

******@GREYSTAR.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)>'