Hello Vanna,
Submitting your e-mail address to a web site is only one way you could be receiving SPAM.
Outlook address book's for example, are often attacked, and the address's within them are often used, so you, or a friend using Outlook Express, he/she may be, or at some point been infected.
There are many others, but I've personally found SpamJab good for filtering SPAM (
spamjab.com: Protecting families from Spam)
Also, it may be good for you and your freinds to go throgh PCHF Prework on my signature to clear yourselves of any malware.