That is why you HIDE this question after you tested it!

for me the workflow could be the following:
- anonymous survey 1 with an email address question
- afterSurveyComplete an email will be send with a link to that email address
- onClick on this link a token will be generated in survey 2
- token (participant) will be invited to survey 2

requires some plugin development knowledge

bismark wrote:

for me the workflow could be the following:

 

This workflow is begging for work. LimeSurvey has no way to resolve mail server issues (e.g. delays).
There is a risk of a bottleneck if an email needs to be sent at the end of the survey.
Delivery issues/greylisting of the mail server will cause a delay between the completion of the first survey and the second survey.
People will reach out and ask why they haven't got received an email.

The topic starter would like to ensure two points:
1.There will be two databases: one for the responses and one for the participants' emails
2.Preventing an anonymous survey from being run multiple times.

The solutions proposed here in this thread are to ensure that respondents do not bypass the first survey to enter the drawing with a valid entry.
As long as respondents only have one email address, you can ensure that they only enter the draw once. This may be the case if you limit the sweepstakes to one company, but not in the "wild". Everyone can have multiple email addresses.

So participants can enter the survey more than once, and as long as they complete the first survey and have an additional email address, they can enter the draw more than once.

Other survey tools offer a question type for personal data which will be saved in a separated database table without creating two surveys.