If you are using our internal Email module to send out your survey then you should not use the Survey Link in the messages. Instead, to properly collect nominative respondent data it is important NOT to alter the [$-link-$] or [$-url-$] tags. These and other such tags are taken care of automatically by our emailing system they generate encrypted links that allow the system to collect nominative data based on the information you placed into the contact list used to send out the emails.
If you are using your own independent email such as Gmail, Yahoo mail, or others, and you used the Survey Link in these emails, then turning anonymous data into nominative data is possible.
In order to do this you must include form type questions in your survey such as name and email. When editing these questions in the Survey Editor module, you need to check the box "Add the respondent in Contacts" box. This way all respondents who answer these questions, will be added to your contacts in Contact Manager.