After you added the survey a new column will be shown. This is the part where you can send the survey.
You need to select particular mail list for this survey. You can also select multiple mail lists
Select the desired mail lists and click send. All the emails will be added to Cron Job queue.
The general purpose of the mail lists feature is used for sending surveys.
Give your mail list name and the custom fields feature is optional. The custom fields feature is if you want to add firstname,lastname, etc.. for this email
After you have created this mail list open the list and you will be able to add new emails.