in my opinion, a sandbox is a prison for thoese people with criminal suspect. if without some proof, the google must not catch you. what proof make google to catch? In my opinion, excessive SEO result in this directly, especial for new site. How to do? For new site, do not have SEO in the begining. you place some product and news, 4-5piece per day. then, do it and last half an month. when the situation is stable, and i think you also enter the gate of google. then, you make SEO works by youreself.
Basically, if you're being sandboxed - it usually means that Google doesn't know what to make of your site yet. They can sandbox you for weeks even months. Just make sure your site is legitimate (i.e. - no MFA sites, etc.) and you'll be lifted out and placed where Google see's fit. Otherwise they will totally exclude your site from Google. Hope this helps, Artemis
Sandbox is the process of the Google or any other search engine It is the process in which new website is put in Sandbox( it is a internal process of Google) duration may be 1 month or so it depends upon the sites quality.
Google check the actual position (popularity) of the website by this method, it checks that a website actually have the currently page rank or not. & after releasing from the Sand box a website has a good page rank.