Big questions to be answered

I want to know how spammers have got my e-mail address as I never use the PlusNet one despite being a customer for nearly 5 years and I have just left the first post ever on their forum.

The only reason I check my PlusNet e-mails is I have done so since day 1, using Outlook to receive notification of billing, etc. This therefore in my opinion disproves all the theories about people using webmail, spammers looking at the forums and working out addresses, and so on.

Once it has been determined how they got my address I want to know what other information they now have about me.