The first things that comes to mind is spam, I know, but taking a closer look lead me to see that when a user registers for an account, the validate link they need to click is cut off when using hotmail.See the attached image, I've tested multiple times, and after speaking to other users at my site, they have encountered it too.You can add receipt validation code to your application to prevent unauthorized copies of your application from running.Refer to the license agreement and the review guidelines for specific information about what your application may and may not do to implement copy protection.My concern is that when a user clicks the link, they believe that they have validated their account and proceed to delete the email.This is because when they click the link, they are told they cannot use the validation link more than once and prompted to sign in, which they can do - but only in their pre-authorised role, not as an authenticated user.
In the past, client-side validation could only be achieved using Java Script or using libraries from frameworks (think j Query validation plugin).
It is a common maxim in security to trust nobody, hence never trust the user to enter correct or valid form values.
For example, in an email form field, instead of entering a valid email address, the user might enter an invalid one or malicious data obviously ignoring the intent of the request.
This form attribute indicates what kind of input control to display such as the popular validates the field to ensure the entered data is in fact a valid email address.
If the field contains an invalid value, the form cannot be submitted for processing until it is corrected.