Spam List
Sometimes the email address is eventually discovered by hackers and can be included in a Spam list.
Email addresses may have been collected through comments on blogs, social networks or even in articles and presentations published online where the email is displayed as a form of contact.
This does not mean that your computer has been hacked, or something similar has happened.
However, that email account becomes a target for more Spam, and can also be something for malicious links and bangs.