A site is sandboxed when it is new and does not rank for keyword phrases that are not incredibly competitive (such as a unique company name) in Google after making the page "search engine friendly" and after being indexed. check this out: http://www.seroundtable.com/archives/001963.html
One of my sites has an older domain name (5 years old), but it hasn't been used in some time. I've started using this domain, does this help me avoid that sand box, or do I have to do my time like everyone else?
You'd better check the following three factors to see 1. The site is on a new domain and less than about 1 year old 2. The keywords you are trying to rank on are considered competitive. 3. Most of the pages of the site has been indexed by Google. If three 3 YES, then u may be sandboxed!
your site is sandbox if your site is new and your page rank is gray or unranked. but is the old domain might be sandbox too?
One more thing, sometimes (not so frequentlly) a website is banned by Google. Make sure you keep all Google instructions for webmasters.
if it ain't indexed by google, has links from site's indexed by google pointing to it, then it's sandboxed. If it's never been listed by Google then it's new and will be sandboxed for up to 3 months. If it was previously indexed by Google and now sandboxed, then you've used some form of spamming of keywords, poor web design technique or black hat SEO technique.
according this thread http://forums.digitalpoint.com/showthread.php?t=71522 Doing a search for allinanchor:"keyword" is the best way to tell. My general rule is if you have go through and search page by page looking for your URL and find it then you are not in the sandbox. But if you get tired of looking and your fingers start to hurt and you quit before you find it then you are in the sandbox.