Outlook.com has blocked my messages

For Outlook.com, this is typically a temporary sending restriction triggered by spam protection, even when the daily total has not been exceeded. Group sends can still be blocked, and each recipient in a group counts toward sending limits.

Use this path:

1. Wait 24 hours and try again with a simple test message.
   • Send to a much smaller batch first instead of 55 recipients.
   • Avoid links or attachments in the test message.
2. Check whether the account is temporarily blocked.
   • Use the Sign-in Helper to unblock the account.
   • If password or verification is required, complete that flow.
3. If Outlook.com still cannot send mail, verify the mailbox is not full.
   • If Outlook.com mailbox or Microsoft cloud storage is full, sending and receiving mail is blocked.
   • Check mailbox/storage usage and clear space if needed.
4. If the issue continues, use Outlook.com support.
   • In Outlook.com, select Help on the menu bar, enter the issue, then scroll to Still need help? and select Yes.
   • If sign-in is also failing, use the support path provided for account sign-in problems.

Important details for this scenario:

• A Microsoft 365 Family subscription does not prevent Outlook.com anti-spam sending restrictions from being applied.
• Large recipient groups can trigger the restriction even when the account owner believes the daily volume is low.
• Newly changed account/address activity can also lead to temporary restrictions.

References:

• Unblock my Outlook.com account
• Can't send or receive email in Outlook.com
• Outlook.com has blocked your message - Microsoft Q&A
• Group email function is blocked - Microsoft Q&A