Outgoing Hotmail emails incorrectly blocked as spam (554 5.7.520)

Question

I am a retired person who does small Santa appearances for a few weeks each Christmas. I send simple one‑to‑one booking confirmation emails to long‑term clients. These are not marketing emails, bulk mail, newsletters, or automated messages.

I recently changed my email address from my old provider to a Hotmail address. Since switching, my legitimate booking emails are being blocked with error 554 5.7.520 “Message blocked because it contains content identified as spam.”

I am only sending normal personal messages to individual clients, but Outlook.com is incorrectly flagging them as spam. Could someone please review my account and remove any incorrect spam flags or restrictions so my booking emails can be delivered normally?

Here is an example of the type of message that gets blocked (with personal details removed):

“Hi, just letting you know my email address has changed. Please update your records.”

Thank you for your assistance.

Answer 1

Hi Peter Brain

I’m sorry that your legitimate booking confirmation emails are being blocked, especially when you are only sending individual messages to long-term clients rather than bulk or marketing emails.

The 554 5.7.520 message indicates that the outgoing email was blocked because its content was identified as spam. As a quick test, please create a completely new plain-text email in Outlook.com and send it to one recipient without a signature, links, images, or attachments. Please do not resend or forward the previously blocked message.

If the new plain-text email is still blocked, the issue may require an account-level review by Microsoft Support.

• Go to Contact Us: https://support.microsoft.com/en-us/contactus
• Click Show expanded list of products
• Select Outlook > Get Home support
• Type Outlook live chat in the search box, then select Get Help > Contact Support
• If you can’t sign in to the affected account, sign in with a different Microsoft account to access support options
• Under Products & Services, select Other Products > Outlook, then choose Chat with a support agent via web browser

When contacting Support, please include the complete non-delivery report, the date and time of the failed message, whether this happens with multiple recipients, and whether a plain-text email without links, a signature, or attachments was also blocked.

Please note that this is a user-to-user support forum. Moderators, contributors including external Microsoft employees cannot directly intervene in Microsoft product features or access back-end systems. Our role is limited to providing technical guidance on reported issues, requests, or ideas only.

I hope the Outlook.com Support team can review the false-positive spam classification and help restore normal email sending.

Thank you for your understanding. 

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