usability - What is behind entering email twice for registration?

What do you think to ask the email twice for registration?

The context is this: In the e-commerce checkout/registration process where the email is mandatory to save cart or to proceed to the checkout, it's better to ask just one time the email and the pass twice or it's better ask the email and password twice to be sure the user fill correctly all the fields.

In the first case the risk should be that users can might some mistake and fill the email form wrong, the second case the risk should be to abandon the registration/chechout because is frustrating.

Answer

The second time you are asked to enter your email you may notice it says "confirmation." That's all it is really, just confirmation that you are entering the correct email.

In some instances, asking for an email twice is crucial. Consider signing up for an email list for example. If the user makes a mistake and enters their email incorrectly, they may leave the website and never realize they entered the wrong email.

In a case where a mandatory email confirmation will be sent right after sign up, you can forego the confirmation and instead just provide a link to change the email address they entered if they don't receive the confirmation. In this scenario, you are appealing to the large majority of users (the ones that will enter their email correctly the first time) by providing less resistance to sign up. For the small majority that will make a mistake, you are allowing them to repair their mistake and have thus covered all of your bases.