However, not sure what are the real advantages of using anonymous tokens
There is no, what you might call "advantage".
But you can assure your respondents that their name and email cannot be merged with their answers.
As you see, there are different types of surveys:
1. The open survey.
Here anybody who knows the general link to the survey is able to answer.
And of course your answer table doesn't contain any personal data.
2.The closed survey
To conduct a closed survey you need a participants table. So only persons who are in this table are allowed to answer the survey. Therefore they receive a unique token (like password) which they have to enter at the start of the survey.
2.1. not anonymous
In this case your answer table contains the personal data (name, email, token) of the respondents
2.2. Anonymous
In this case your answer table does NOT contain these data.
Nor does the ID match the ID in the participant table. It's just an autoincrement number.
Additionally, I would like to know if it´s possible to conduct the survey in closed mode with anonymous tokens? Meaning that only participants from the email list can fill out the survey?
As you might have seen already:
When you activate a survey you are first asked, if you want to have "anonymous" answers.
After clicking "Save and ..." you are asked if you want to create a participants table (closed mode).
And "anonymous tokens"? Here you are a little bit confused.
Is it possible to send reminders only to those participants who have not yet replied and still keep the survey completely anonymous?
These are two different things.
As said and also here in the manual
www.limesurvey.org/manual/Survey_partici...onymous_responses.3F
You send a reminder to a person of the participants table, who do not have a flag "already answered". So you know WHO answered and WHO did not, but you do not know WHAT they answered.
Joffm