You should be getting much spam at all as the sky email program is powered by Google who operate their own spam filters. You need to log-in here:
https://mail.google.com/a/sky.com
Click on 'all mail' then highlights any mails there that are spam, when you have done this simply hit the 'report spam' link and this will reclassify them as spam.
Regarding the spam to other people, this is because spam sent their rubbish out in bulk to a lot of people at once so you will see other addresses in them as well, yours will be there as well.