Account got hacked now im flagged as spam and cant send work emails

For a business Outlook on the web account that was hacked and then blocked for spam, two things are needed: securing the account and having the admin remove the outbound block.

1. Confirm and remediate compromise indicators

• Since rules were already found and removed, also check for other compromise signs described in the Microsoft 365 guidance, such as:
  • Mailbox blocked from sending email.
  • Suspicious Inbox rules (especially ones that forward or move mail to unexpected folders).
  • Suspicious messages in Sent Items or Deleted Items.
  • External forwarding recently enabled.
• If any of these are present, follow the remediation steps in the compromised-account guidance to fully secure the mailbox (password reset, MFA, removal of malicious rules/forwarding, etc.).

2. Have the admin clear the outbound spam block Because the hacker sent spam, the account likely hit Exchange Online sending limits and was automatically restricted. This results in NDRs like:

550 5.1.8 Access denied, bad outbound sender

To restore sending:

• Inform the organization’s Microsoft 365/email administrator that the account was compromised and is now blocked from sending.
• The admin should:
  1. Follow the “Secure a compromised email account in Exchange Online” steps to ensure the account is clean.
  2. Go to the Restricted entities page in the Microsoft 365 Defender portal (security.microsoft.com/restrictedusers) and unblock the user account.
• After unblocking on the Restricted entities page, all restrictions are typically removed within about an hour and normal sending should resume.

If this is a personal Outlook.com account (not business), use the Outlook.com unblock flow instead:

• Go to the Sign-in Helper from the “Unblock my Outlook.com account” article and follow the prompts to remove the block.

If the account was hacked, also follow the general Microsoft account recovery guidance to ensure devices are clean (antivirus scan), password is changed, and account settings (forwarding, connected accounts, automatic replies) are reviewed.

References:

• NDR error code "550 5.1.8 Access denied, bad outbound sender"
• Respond to a compromised cloud email account
• Unblock my Outlook.com account
• How to recover a hacked or compromised Microsoft account