Mailing lists (aol issues)

So I decided to set up a mailing list for my site. Basically its like this, my hosting package comes with SmartList. So what I do is have people that visit the site fill out a form field with their email address, I then take that email address and enter it into my mailing list,list. So when I go to write an email (newsletter) Everyone gets it but aol addresses. I’ve been testing this thing all night and have no idea why this is. Didn’t know where else to post but here in Random. Anyone have anything on this?
I couldn’t find any docs online.