Sandbox is a negative for your web site. It’s called to Google’s block to your web site. After this blocking , the web site will show at the end of searching although it has too many keywords about it’s web site. It will exite between 1 and 6 mounth to recover from Sandbox. That’s why , the web site try to be shown on the top in search engines with making spam and google doesn’t allow this.
Sandbox filter and google ban are apart from each other. If you drop in Sandbox , It does not mean that you are banned from google. If you search your domain name in google and you don’t get result. probably you are banned from google. You can also understand this If you look up log files of your web site. You can see that google boot came or not. If you have a banned web site , google boot does not come to your web site.
You can leave sandbox. If you reduce spams in your web site , you can leave from sandbox. If you continue to improve your web site, you should leave from sandbox.