If you do not want to receive further emails from a service after the registration which asks you to click the link they have sent to your email inbox then you can use temporary inboxes to register and activate the service. And if you are suspicious about a site that they can use your email for spams then also you can use their service without getting spammed.
To get a temporary mail just open any of the website links given below and you will have an email address without typing a single word. Just copy that and paste wherever you want to use it. Thats all :) This inbox would be temporary and exist for few minutes only. They don't need any registration or filling a long and boring form to sign up and get a temporary inbox.
Below is the list of all major and the best temporary inbox and email services provider that you can use.
Best Temporary Email and Inboxes
http://10MinuteMail.com/
http://www.MinteMail.com/
http://www.IncognitoMail.com/
http://www.Jetable.org/en/index
http://www.SpamSpot.com/
http://www.GuerrillaMail.com/
http://www.TemporaryInbox.com/
http://www.MailEater.com/
http://www.MailExpire.com/
http://www.Mailinator.com/
http://www.SpamBox.us/
http://www.MyTrashMail.com/