E-mail has been hijacked.

[LAS14]

We discovered that hundreds of e-mails had been sent from one of our Outlook.com accounts (we have two in the house, and use each on separate computers.) We're prevented from sending e-mails because of a daily limit. Here are two screen shots of the Sent folder.

Today one new e-mail appeared in Sent at about the time we booted up the computer. We shut it down pretty quickly.

What should we do?

EDIT: In case anyone else is following this. We found messages in a backup gmail account that said that apps had been added to our Microsoft account. We removed the apps. We hope this has fixed it.

TIA
LAS

https://imgur.com/a/oeH8MKG

[TwilightZone]

1. You more than likely have a virus or malware.

The malware is generating the e-mails.

Download the free version of Malwarebytes and run a scan. Let it remove anything it finds.

https://www.malwarebytes.com/

Also, change the password on the outlook.com account immediately in case someone has your login credentials and is using your account to send mail.

[LPBBEAR]

2. Some suggestions

In general:
1. If you are using an email client software (Outlook or Thunderbird for instance) enable text only mode.

2. Use BCC instead of CC when mailing more than one recipient. BCC = BLIND Carbon Copy CC = Carbon Copy

For the current issue:
3. Do a thorough Virus/Malware scan of your computer if you are using Windows. Do complete updates of your scanning software first. Reboot the system with your network cable unplugged or wireless off if you are using wireless. Choose the most thorough deep scan available for your scanning software. If the scanning software doesn't correct the issue you may need to seek outside help.

For the future:
4. Stop using Outlook and/or Outlook.com