So many people make the mistake of mistyping their emails - gmali.com instead of gmail.com being a very frequent example - and spambots sign up with fake accounts here often, so we clean out accounts that have never been logged into after a few days. If you log in, even just once, and begin filling out your personal page and add your personal avatar image, you're safe but if you wait a full week for whatever reason it's likely that your account was deleted with the other dead ones.

Unlike other websites, I actually cull the accounts to clean out spammers and simply "dead accounts" (which could be due to a host of reasons, like misspelled emails or whatnot) on a regular basis. We're striving to have an active user number to brag with, not an inflated registered user number where thousands have never logged in.