Why is email activation useful?
I just want to ask you why is email activation useful. I mean when you register on a website, many ask you to activate your account by email. Is this for preventing spam, or just for websites to be sure you entered a real email address, to send you emails in the future? If it is for spam, how is that preventing spam, cant bots access mail, or what?
Answer
EMail activation is primarily used to ensure that you're signing up with a "real" email address, and also one that you have access to (and therefore, presumably, are the legitimate "owner" of the email address).
This enables the website to be able to contact you at some later date since it now has a legitimate email address for you, the user. This can be used for password resets, or general communication etc.
EMail activation also effectively prevents you from signing up your friend/enemy even though you know their email address, unless you also have access to their email account, which is unlikely.
This is mostly used to stop one person from registering another person's email address with a site in order to generate spam from the site to the innocent victim. Most website's that employ such "email validation" will ignore sign-up requests unless they are "verified", usually by clicking a "secret" link or entering a "secret" code back on the website that is originally sent in the email message.
Many legitimate website users are sometimes distrustful of giving their "real" email address to websites for fear that they themselves will recieve spam from the website. Many times, this depends upon the user's trust of the website that they are visiting. To this end, there are a number of services (such as Mailinator, SpamGourmet, and many others) that legitimate and non-legitimate users alike can employ to provide a "real" email address that is accessible by the user, yet also disposable and temporary to allow the user to ensure that they recieve no spam to their real email address.
This, to some degree, can defeat the effectiveness of an "email validation" system employed by a website, since the website now cannot guarantee that the user (identified by the email address) is "genuine" (i.e. it's not a "throwaway" email address). To this end, many website will prevent users from registering with an email address on a known "disposable" domain.