The website URL field is required to set up a new turboSMTP account, but there are lots of valid options for this field. Here are some alternatives that we suggest if you don't have a website.
Use a blog
If you have a WordPress, Blogger, or Tumblr account (or another blogging service), you can link to your blog.
Create a Personal Page
Some services offer a quick personal landing page that functions like an online business card. For instance, you can try About.me or Flavors.me.
Create a Website
If you want to get a website but you aren't a designer, Wix, Weebly, Squarespace and Virb are web publishing tools that let everyone to have a website.