emails bouncing back

Question

Hello;

When I try to send an email to myself i get a bounce back email from

and this message below.

from "******@outlook.com"

Delivery has failed to these recipients or groups:

Your message wasn't delivered because the recipient's email provider rejected it.

Message blocked because it contains content identified as spam. AS(4810)>'

How can I fix this so it can work again?

Answer 1

Can you use the instruction here, change the email to plain text or rich text format (basically avoid the html format) and see if it goes through:

https://support.microsoft.com/office/change-the-message-format-to-html-rich-text-format-or-plain-text-in-outlook-338a389d-11da-47fe-b693-cf41f792fefa

Answer 2

The message is being rejected by the receiving email system because it classifies the content as spam. This is a non-delivery report (NDR) generated when the destination server blocks the message.

To address this:

1. Verify the message content
   • Remove any content that might look like bulk mail or phishing (many links, URL shorteners, misleading subjects, or repeated identical text).
   • Remove or reduce attachments, especially if they are large or uncommon file types.
   • Send a very simple test message (plain text, short subject and body) from the same account to the same address to confirm whether it still gets blocked.
2. Check if the address is valid and working
   • Since the message is to the same address, confirm that the mailbox is working by sending from another account (for example, from a different email provider) to this Outlook address and confirming delivery.
3. Use Outlook on the web to test
   • If the bounce happens when sending from a client (like the new Outlook for Windows), sign in to Outlook.com and send the same test message from there. If it works from Outlook.com but not from the client, the issue may be related to how the client is composing or submitting the message.
4. Reduce recipients and retries
   • If the same message is being sent to many recipients (including the self-address), try sending only to the Outlook address to see if the bulk nature of the message is causing it to be flagged.
5. If the problem persists
   • Because the error indicates the receiving system is blocking the message as spam, and self-sent mail is affected, this may require provider-side adjustment. Use the non-delivery report details when contacting support so they can check why messages from this account are being classified as spam and, if necessary, adjust filtering or unblock the account.

If other messages (with different content) send and receive successfully, focus on changing the content and format of the blocked messages. If all messages to this address are blocked, provider-side investigation is required.

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References:

• Sent email in Outlook.com comes back "delivery failed"
• Message Trace FAQ in Exchange Online