First question: What is Incredimail?
I just had a quick look at the Incredimail website and it seems to be some kind of email program which gives you adverts. I'm not sure what the benefit is for you.
So, why don't you use a normal email program? Windows Vista includes an email program called Windows Mail.
If for some reason you want to use Incredimail, contact their technical support people via the form at:
http://www.incredimail.com/english/contactForm .asp?deptSelect=1