Hello I just bought a premium domain (highly relevant keyword) but it was just running domain for sale ads until now. If I establish the site now will it still be sandboxed or since it is 3yrs old is it likely not to be? Thanks.
Sure it CAN be sandboxed. Google can filter a VERY old domains for a radical content, IP, DNS changes.
SandBox can be started again if you'll change contant completely. IP and DNS do not have any impact (this is a standart procedure of changing datacenter within the same hoster, or changing hoster company, or doman name provider)
The best way i feel is to get links from authority sites. This way you should be out of the box in no time
I just thought only new sites will be sandboxed by Google. I gotta take more care to more existing sites.