You can add an email address element to your survey that can be used to add respondents as new contacts to your address books, and this can allow any other information captured to be added to contact data fields.
Configuring an email address element
If your template doesn't already feature an email address field, you can select the Email address element from the 'Build' side panel and drag it in. Click on Type question here to then enter your text for it.
In the side panel, you'll notice that email validation is automatically configured for the element. However, you do have the choice to write your own validation error message if you wish.
Assigning to contact data fields
If you're assigning questions to contact data fields throughout your survey or form, then you'll need to have this element assigned to your email address contact data field. This will ensure you're successfully collecting and assigning all the data you require to your address books. You can find out more about this in Assigning questions to your contact data fields.