How to stop my Outlook email from sending spam messages, as my emails are not being delivered

Question

How to stop my Outlook email from sending spam messages, as my emails are not being delivered

Hazel Dewey 25

my outlook account has been compromised and was sending spam. Now all my emails are not delivering messages.

0 comments

Answer accepted by question author

Sin-D 12,260 Microsoft External Staff Moderator

Hi Hazel,

Thank you for reaching out. If your Outlook account was compromised and is now unable to send emails, please immediately secure your account:

Change your password immediately to a strong, unique one.
Enable Multi-Factor Authentication (MFA) to prevent future unauthorized access.
Review your recent sign-in activity in your Microsoft account security page to confirm no ongoing compromise.

After an account is hacked, most accounts will have suspicious sent emails. Check whether there are any unusual emails in the Sent folder. Also, review the Rules and Forwarding settings. If there are any rules that prevent you from sending new emails, remove them all.

If the issue persists, please attach a screenshot of the error you receive when trying to send an email. Most sending errors will display an error message; if not, the emails might be blocked by hidden rules.

If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

Best regards,

Hazel Dewey 25 Reputation points

2025-09-19T08:45:37.01+00:00

Error message is

Delivery has failed to these recipients or groups: this message couldn't be delivered because the sending email address was not recognised as a valid sender. The most common reason for this error is that the email is, or was, suspected of sending spam.
Sin-D 12,260 Reputation points Microsoft External Staff Moderator

2025-09-19T11:31:44.9933333+00:00

Hi Hazel,

Your issue might be a bit complicated. First, please check the domain where you received the error. Is it from a spam email, or does the error occur whenever you send an email?

To be safe, change your account password immediately. If you received the error as part of a spam email, report it to help keep your account secure.

Most of these errors happen when using a custom domain for an organization. If you are an end user, ask your IT team or admin to remove any restrictions on your account. They can follow this guide: Remove blocked users from the Restricted entities page. If you are the admin, make sure your domain has SPF and DMARC set up correctly, as misconfigurations can cause issues. Many email service providers now require verification of SPF, DKIM, and DMARC. Ensure these records are properly configured. You can check them at https://mxtoolbox.com/.

If you have further questions, please let me know.

Best regards.
Hazel Dewey 25 Reputation points

2025-09-20T11:04:26.4633333+00:00

Asked around and after changing password and checking settings I contacted my email provider as my email had been added to a banned user list (because of the previous scamming). This is usually the remedy. Now sorted so lesson is to change password regularly and check for suspicious log ins.
mai hunter 0 Reputation points

2026-01-13T22:29:34.53+00:00

Hi, this has also happened to me and my email is still sending out spam please help

4 additional answers

Your answer

Hazel Dewey 25 Reputation points

2025-09-19T08:45:37.01+00:00

Error message is

Delivery has failed to these recipients or groups: this message couldn't be delivered because the sending email address was not recognised as a valid sender. The most common reason for this error is that the email is, or was, suspected of sending spam.
Sin-D 12,260 Reputation points Microsoft External Staff Moderator

2025-09-19T11:31:44.9933333+00:00

Hi Hazel,

Your issue might be a bit complicated. First, please check the domain where you received the error. Is it from a spam email, or does the error occur whenever you send an email?

To be safe, change your account password immediately. If you received the error as part of a spam email, report it to help keep your account secure.

Most of these errors happen when using a custom domain for an organization. If you are an end user, ask your IT team or admin to remove any restrictions on your account. They can follow this guide: Remove blocked users from the Restricted entities page. If you are the admin, make sure your domain has SPF and DMARC set up correctly, as misconfigurations can cause issues. Many email service providers now require verification of SPF, DKIM, and DMARC. Ensure these records are properly configured. You can check them at https://mxtoolbox.com/.

If you have further questions, please let me know.

Best regards.
Hazel Dewey 25 Reputation points

2025-09-20T11:04:26.4633333+00:00

Asked around and after changing password and checking settings I contacted my email provider as my email had been added to a banned user list (because of the previous scamming). This is usually the remedy. Now sorted so lesson is to change password regularly and check for suspicious log ins.
mai hunter 0 Reputation points

2026-01-13T22:29:34.53+00:00

Hi, this has also happened to me and my email is still sending out spam please help

Answer 1

paulr0511 48,365 Independent Advisor

Glad to know that this has been sorted out and it is also best to add an additional layer of security on your email account like having two factor authentication to avoid unauthorized or suspicious access or activities that can be tied to your account.

0 comments

Answer 2

Sin-D 12,260 Microsoft External Staff Moderator

Hi Hazel,

I’m really happy that your issue has been resolved. I understand that dealing with a compromised account can be very frustrating, and I’m glad you didn’t encounter any more serious problems related to your account.

I also truly appreciate that you shared this information to help other users who might face the same issue. Your contribution helps others understand the situation better and take preventive measures. That’s a great way to support the Microsoft Community. Thank you so much!

Best regards.

0 comments

Answer 3

Hazel Dewey 25

Used the steps recommended ie change password, add two-stage verification, check virus software, but the last stage is very common, I couldn’t send emails as it had been added to a blocked list so had to contact my email provider BT to unblock.

0 comments

Answer 4

paulr0511 48,365 Independent Advisor

You may continue to follow the advise from Sin-D and then you can also check the initiative on my previous response and hopefully this gets sorted out.

0 comments