Error message on all outgoing emails- Message Blocked AS (4810)

Leanne 0 Reputation points
2026-09-09T07:52:06.5033333+00:00

Good afternoon,

I have used hotmail for years and never had any issues, however I sent up a new email address last week and now all my outgoing emails are bouncing back and coming back with a message saying ' Message blocked because it contains content identified as spam. AS (4810).

I have tried different email addresses, emails with different text, emails with and without attachments, emails with and without email signiture and does test emails and all are coming back with the same error message.

I feel that my account has had a spam marker put on it, please can i have some help in how to stop this from happening?

Outlook | Web | Outlook.com | Email
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  1. SD - IA 178.7K Reputation points Independent Advisor
    2026-09-10T10:48:09.2033333+00:00

    Hi there,

    I just wanted to follow up and check whether the steps I provided helped resolve the issue.

    If the issue is still not resolved, please let me know. I’ll be happy to continue assisting you.

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  2. SD - IA 178.7K Reputation points Independent Advisor
    2026-09-09T08:52:26.9866667+00:00

    Hi Leanne,

    If you have also tried to change to Plaintext as described below, please move to STEP 2.

    1. Open the Gear icon > Settings.
    2. Go to Mail > Compose and Reply.
    3. Change the message format to Plain text.

    STEP 2:

    File a report at the https://sender.office.com portal to resolve this issue. The delist would happen after 48 hours.

    Also restart your router to ensure that the bad IP reputation might not be causing this issue.

    I hope this information helps. If you have any more questions, don't hesitate to reach out. Wishing you good luck!

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  3. Leanne 0 Reputation points
    2026-09-09T07:54:33.42+00:00

    I have tried this and done test emails to different email addresses and does not work

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  4. AI answer

    2026-09-09T07:52:25.8333333+00:00

    For 550 5.7.520 / AS(4810), the message is being identified as spam by Microsoft filtering. Since it happens on all outgoing messages, including simple tests, focus on account and message checks rather than the recipient.

    1. Send a plain-text test message from Outlook on the web with no attachment, no links, and no signature.
      If that works, add content back gradually to find the trigger.
    2. Review message content for common spam triggers.
      Messages are more likely to be flagged when they contain:
      • excessive links
      • URL shorteners
      • embedded scripts
      • image-only content
      • complex HTML formatting
    3. In Outlook.com, review mail settings that could affect sending or handling:
      • Settings > Mail > Junk email
      • Check blocked senders/domains and any unusual entries
    4. If attachments are involved, test without them first. Some reports indicate attachments, especially combined with HTML formatting, can increase the chance of spam filtering.
    5. Verify the Microsoft account status at the account portal to make sure identity verification or account checks are complete.
    6. If simple plain-text messages with no links or attachments still fail, contact Outlook.com support from within Outlook.com:
      • Sign in to Outlook.com
      • Select Help on the menu bar and enter the issue
      • If self-help does not resolve it, go to Still need help? and select Yes
      • If Help does not open, sign in, then select the ? at the top of the Outlook.com window
    AI-generated content may be incorrect. Read our transparency notes for more information.

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