Hotmail account sending spam

Good morning,
I have been receiving "Delivery Status Notification (Failure) via my Hotmail.
I investigate and realised (like many others) that my Hotmail has been sending random emails to people in my contacts list.
At first I thought that someone has hacked my email account, but now i am unsure, because i have read that it could be a virus/malware/trojan/worm or whatever other rubbish is on my laptop. I have McAfee and i have run the complete scan over night but nothing was found.
Please help me to solve this probelm.
ps. I have read already read the "new members" section and the part about updating and using OTL scan, but I am at work at the moment and would like to make sure before i start running scans and sucg.
Thank you in advance

Hello, and welcome to GeekPolice.

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