I am getting this warning even though I do not send many emails Outlook.com has blocked your message

Stop sending for 24 hours, then test from Outlook.com with one new, plain-text message containing no signature, link, or attachment; this warning can reflect a temporary account-level sending restriction even when only a few messages were sent.

Resolve the temporary restriction

1. Wait a full 24 hours after the most recent blocked attempt.
   Repeated attempts during the restriction may not succeed. A closely matching Outlook.com case recommends waiting 24 hours before testing again.^1^
2. Review the Microsoft account’s security activity.
   • Look for an unfamiliar sign-in, device, or location.
   • If anything is unfamiliar, change the password immediately.
   • Ensure the recovery phone number and alternate email are current.
   Outlook.com can temporarily block an account after unusual sign-in activity, and Microsoft provides an account-unblocking process for that condition.^2^
3. After 24 hours, send a controlled test from Outlook.com on the web.
   • Use one recipient.
   • Create a new message rather than resending the blocked one.
   • Use a short, plain-text subject and body.
   • Remove the signature.
   • Do not include links or attachments.
   Microsoft notes that signatures can sometimes prevent sending, while attachments over 25 MB cannot be sent.^3^

Because the same failure occurs in both the app and web interface, reinstalling or repairing the Outlook app is unlikely to address this account-side restriction. Storage and adding the recipient to Contacts also do not need to be repeated, since those have already been checked.

If the plain test is still blocked

Outlook.com applies limits to daily messages, daily recipients, recipients per message, and recipients with whom the account has no previous sending relationship. Limits can vary by usage history, are lower for non-subscribers, and may temporarily be low for newer accounts.^4^

If the account is new or recently changed, continue with occasional single-recipient messages rather than repeated or grouped attempts. Also ensure the account profile and security information are complete; Microsoft lists current security information and Microsoft Authenticator among the measures that can help establish the account.

If the restriction remains after 24 hours and the simple test also fails:

1. In Outlook.com, select Help on the menu bar.
2. Enter the exact warning text.
3. Complete the suggested troubleshooting.
4. Scroll to Still need help?
5. Select Yes to contact Outlook.com support.^4^

Include the date and time of the last successful message, the blocked test’s time, and confirmation that it failed in both Outlook.com web and the app. Do not include your password or security codes.

References

1. Outlook.com has blocked your message - Microsoft Q&A
2. Unblock my Outlook.com account
3. Can't send or receive email in Outlook.com | Microsoft Support
4. Sending limits in Outlook.com | Microsoft Support