Email registration won't always fix retention problems.<p>In general, if a site forces me to register, and I either (a) don't trust the site ownership/security, or (b) don't yet intend to become a long-term user, I will fall back to using a <a href="http://bugmenot.com/" rel="nofollow">http://bugmenot.com/</a> login or sign up with a disposable email address obtained via a service like <a href="http://mailinator.com" rel="nofollow">http://mailinator.com</a> or <a href="http://10minutemail.com" rel="nofollow">http://10minutemail.com</a>. In general, I find having to verify email addresses tedious and annoying, but it's not generally a deal-breaker.<p>In another post, you mentioned "i do not allow for email address change." That could be a problem for impulsive users considering making the switch from short- to long-term use. Churning email addresses out isn't that hard, if one is so inclined. Ironically, one of the places I think confirmation email might be helpful, is when changing email address. If you force the user to confirm from both addresses, you run less risk that they make a typo in their new address.<p>That's all personal, though. You may want to search for existing conversion/retention research or just conduct some A/B tests.<p>If spammer sign-up is a big concern, and you want to prevent them from mucking up your data, consider something like <a href="http://www.google.com/recaptcha" rel="nofollow">http://www.google.com/recaptcha</a> to deter bots.