Appears a hacker changed my Outlook signature card

Erin Smith 20 Reputation points
2026-08-12T19:07:35.2533333+00:00

Appears a hacker changed my Outlook signature card at 10:52 am est this morning. Ran Malwarebytes and nothing was flagged. Immediately changed my Outlook password.

When sending an email, it shows my email address but the signature card shows the following: (I've filtered my email messages to trash as to not possibly cause others problems for now) How can I fix this?

Clickbuzz Hub 

[Moderator Note: Personal Info Removed]@gmail.com

To:[Moderator Note: Personal Info Removed]

Outlook | Web | Outlook.com | Account management, security, and privacy
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Answer accepted by question author
Chloe-V 12,710 Reputation points Microsoft External Staff Moderator
2026-08-13T08:59:51.52+00:00

Hi Erin Smith

Please note that our forum is a public platform, and we will modify your question to hide your personal information in the description. Kindly ensure that you hide any personal or organizational information the next time you post an error or other details to protect personal data.

I’m sorry this happened. An unfamiliar email signature can indicate that someone accessed your mailbox, so changing your password immediately was the right step. Microsoft also lists suspicious message signatures, forwarding, and inbox rules as possible signs of mailbox compromise.

To remove the signature in Outlook.com:

  • Open Settings.
  • Select Accounts > Signatures.
  • Select the unfamiliar signature, remove it or replace its contents, and select Save.
  • Confirm the correct signature is selected for new messages and replies/forwards.

Please also review:

  • Settings > Mail > Rules and delete any rule you did not create.
  • Settings > Mail > Forwarding and disable any unknown forwarding address.
  • Your Sent Items, Deleted Items, and account sign-in activity for anything unfamiliar.
  • Your Microsoft account security information, and enable two-step verification. Two-step verification makes it more difficult for someone to sign in even if they know the password.

Do not send further messages until the unfamiliar signature, rules, and forwarding settings have been removed.

Please feel free to let me know if you have any further updates, thanks.


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.  

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